Immuno-based botulinum toxin serotype a activity assays

ABSTRACT

The present specification discloses SNAP-25 compositions, methods of making α-SNAP-25 antibodies that bind an epitope comprising a carboxyl-terminus at the P 1  residue from the BoNT/A cleavage site scissile bond from a SNAP-25 cleavage product, α-SNAP-25 antibodies that bind an epitope comprising a carboxyl-terminus at the P 1  residue from the BoNT/A cleavage site scissile bond from a SNAP-25 cleavage product, methods of detecting BoNT/A activity, and methods of detecting neutralizing α-BoNT/A antibodies.

This application is a continuation of U.S. patent application Ser. No.12/723,474, filed Mar. 12, 2010, which is a continuation-in-part of Ser.No. 12/403,531, filed Mar. 13, 2009, which claims priority pursuant to35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No.61/036,723 filed Mar. 14, 2008, all incorporated entirely herein byreference.

SEQUENCE LISTING

The application contains a Sequence Listing that has been filedelectronically in the form of a text file, created Aug. 17, 2020, andnamed “18383-US-CIP1CON1-NTB-SubstituteSequenceListing.txt” (313573bytes), the contents of which are incorporated herein by reference intheir entirety.

The ability of Clostridial toxins, such as, e.g., Botulinum neurotoxins(BoNTs), BoNT/A, BoNT/B, BoNT/C1, BoNT/D, BoNT/E, BoNT/F and BoNT/G, andTetanus neurotoxin (TeNT), to inhibit neuronal transmission are beingexploited in a wide variety of therapeutic and cosmetic applications,see e.g., William J. Lipham, Cosmetic and Clinical Applications ofBotulinum Toxin (Slack, Inc., 2004). Clostridial toxins commerciallyavailable as pharmaceutical compositions include, BoNT/A preparations,such as, e.g., BOTOX® (Allergan, Inc., Irvine, Calif.),DYSPORT®/RELOXIN®, (Ipsen Ltd., Slough, England), PURTOX® (Mentor Corp.,Santa Barbara, Calif.), XEOMIN® (Merz Pharmaceuticals, GmbH., Frankfurt,Germany), NEURONOX® (Medy-Tox, Inc., Ochang-myeon, South Korea), BTX-A(Biogen-tech Ltd., University, Yantai, Shandong, China); and BoNT/Bpreparations, such as, e.g., MYOBLOC®/NEUROBLOC® (SolsticeNeurosciences, Inc., South San Francisco, Calif.). As an example, BOTOX®is currently approved in the U.S. for the treatment of cervical dystoniain adults to decrease the severity of abnormal head position and neckpain associated with cervical dystonia; for the treatment of severeprimary axillary hyperhidrosis that is inadequately managed with topicalagents; and for the treatment of strabismus and blepharospasm associatedwith dystonia, including benign essential blepharospasm or VII nervedisorders in patients 12 years of age and above.

At present the mouse LD₅₀ bioassay, a lethality test, remains the “goldstandard” used by all pharmaceutical manufacturers to express thepotency of their preparations. S. S. Arnon et al., JAMA 285: 1059-1070(2001). In fact, the units on the pharmaceutical preparations' labelsare mouse LD₅₀ units and the number of animals needed to producestatistically useful LD₅₀ data is large. The advantage of the mouse LD₅₀bioassay is that it measures all the steps necessary for botulinum toxinuptake (e.g., toxin binding to a cell surface receptor, internalizationof the toxin-receptor complex, light chain translocation into thecytoplasm, light chain cleavage of substrate), instead of merelydetermining the activity for only part of this intoxication process,such as, e.g., in vitro assays that only measure light chain enzymaticactivity. Unfortunately, the mouse LD₅₀ bioassay suffers from manydrawbacks including high operational cost due to the large numbers oflaboratory animals required, a lack of specificity since all BoNTserotypes will cause the same measurable end-point, and the potentialfor inaccuracy unless large animal groups are used. In addition, animalrights groups have exerted pressure on regulatory agencies in the U.S.(FDA/NICEATM/ICCVAM) and Europe (MHRA and EDQM), and on pharmaceuticalcompanies manufacturing botulinum neurotoxin products to reduce animaltesting and more importantly replace the mouse LD₅₀ bioassay for productrelease. The regulatory agencies are engaging pharmaceutical companiesto apply the three “Rs” principle to the potency testing of botulinumneurotoxins: Reduce, Refine, Replace. D. Straughan, Progress in Applyingthe Three Rs to the Potency Testing of Botulinum Toxin Type A, Altern.Lab. Anim. 34(3): 305-313 (2006). In recent years, several steps havebeen already taken to reduce and refine the mouse LD₅₀ bioassay in orderto standardize the protocol and produce more consistent data using feweranimals per assay.

Thus, a simple, reliable, validated and governmental agency acceptablebotulinum toxin activity assay that can evaluate the integrity of allthe steps necessary in botulinum toxin uptake would be of significantvalue because such a non-animal based assay would alleviate the need foranimal testing and all the disadvantages, costs and ethical concernsassociated with this type of animal-based assay. The presentspecification provides novel compositions, cells, and methods forassaying the activity of a botulinum toxin A useful for variousindustries, such as, e.g., the pharmaceutical and food industries, andprovides related advantages as well. Such compositions, cells, andmethods do not use live animals or tissues taken from live animals, butcan evaluate all the steps necessary for neurotoxin action.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are schematics of the current paradigm of neurotransmitterrelease and Clostridial toxin intoxication in a central and peripheralneuron. FIG. 1A shows a schematic for the neurotransmitter releasemechanism of a central and peripheral neuron. The release process can bedescribed as comprising two steps: 1) vesicle docking, where thevesicle-bound SNARE protein of a vesicle containing neurotransmittermolecules associates with the membrane-bound SNARE proteins located atthe plasma membrane; and 2) neurotransmitter release, where the vesiclefuses with the plasma membrane and the neurotransmitter molecules areexocytosed. FIG. 1B shows a schematic of the intoxication mechanism fortetanus and botulinum toxin activity in a central and peripheral neuron.This intoxication process can be described as comprising four steps: 1)receptor binding, where Clostridial toxin binds to a Clostridialreceptor complex and initiates the intoxication process; 2) complexinternalization, where after toxin binding, a vesicle containing atoxin/receptor system complex is endocytosed into the cell; 3) lightchain translocation, where multiple events are thought to occur,including changes in the internal pH of the vesicle, formation of achannel pore comprising the H_(N) domain of Clostridial toxin heavychain, separation of the Clostridial toxin light chain from the heavychain, and release of the light chain and 4) enzymatic targetmodification, where the light chain of Clostridial toxin proteolyticallycleaves its target SNARE substrates, such as, e.g., SNAP-25, VAMP orSyntaxin, thereby preventing vesicle docking and neurotransmitterrelease.

FIGS. 2A-2B show a comparison of BoNT/A uptake in four cell lines byWestern blot analysis. FIG. 2A shows a graph of SNAP-25 cleavage productdetected based on amount of BoNT/A used to treat the cell line. The datawere analyzed in SigmaPlot using a 4 parameter logistic model and EC₅₀values were obtained for each cell line. Ranking of SNAP-25 cleavageproduct signals detected was: SiMa>>Neuro-2a>LA1-55n>PC12. FIG. 2B showsthe signal-to-noise ratios of the raw signals at 300 pM vs. 0 pM and 1.2pM vs. 0 pM were calculated for the assay. SiMa cells generated thehighest signal-to-noise ratios and the lowest EC₅₀ values.

FIG. 3 shows optimization of cell differentiation media for establishedcell lines useful in an immuno-based method of detecting BoNT/A activitydisclosed in the present specification.

FIG. 4 shows optimization of cell differentiation time for cellscomprising an established cell line useful in an immuno-based method ofdetecting BoNT/A activity disclosed in the present specification.

FIG. 5 shows optimization of BoNT/A treatment of cells comprising anestablished cell line useful in an immuno-based method of detectingBoNT/A activity disclosed in the present specification. The resultsindicate an EC₅₀ of less than 2 pM was achieved with any of the BoNT/Atreatments tested.

FIG. 6 shows the sensitivity of an immuno-based method of detectingBoNT/A activity disclosed in the present specification. The resultsindicated that uptake of BoNT/A by the cells took less than one minutebefore producing significant amounts of SNAP-25 cleavage product overbackground.

FIG. 7 shows the specificity of an immuno-based method of detectingBoNT/A activity disclosed in the present specification. The resultsindicate that the immuno-based methods of detecting BoNT/A activitydisclosed in the present specification can measure all the stepsinvolved in BoNT/A intoxication.

FIG. 8 shows a dose response curve of differentiated SiMa cells treatedwith a BoNT/A complex using an immuno-based method of detecting BoNT/Aactivity disclosed in the present specification.

FIG. 9 shows the results of an immuno-based BoNT/A activity assay for aformulated BoNT/A pharmaceutical product using an immuno-based method ofdetecting BoNT/A activity disclosed in the present specification.

FIGS. 10A-10B show the detection of neutralizing α-BoNT/A antibodies inhuman serum using an immuno-based method of detecting BoNT/A activitydisclosed in the present specification.

DETAILED DESCRIPTION

The present specification provides novel assays for determining thepresence or absence of an active BoNT/A in a sample and for determiningthe activity/potency of a BoNT/A preparation. The novel cell-basedassays disclosed in the present specification rely on cells, reagentsand detection methods that enable the assay to detect picomolarquantities of BoNT/A in a sample. The cell-based assays disclosed in thepresent specification reduce the need for animal toxicity studies, yetserve to analyze multiple functions BoNT/A, namely, binding and cellularuptake of toxin, translocation into the cell cytosol, and proteaseactivity. As discussed further below, the novel methods and compositionscan be used to analyze crude and bulk samples as well as highly purifieddi-chain toxins and formulated toxin products and further are amenableto automated high throughput assay formats.

Thus, one aspect disclosed in the present specification providescompositions for producing α-SNAP-25 antibodies that can bind an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product.Compositions can comprise an adjuvant and a composition including aSNAP-25 antigen, a carrier linked to a SNAP-25 antigen, or a carrierlinked to a flexible spacer linked to a SNAP-25 antigen, where theflexible linker intervenes between the SNAP-25 antigen and the carrier.It is envisioned that any and all SNAP-25 antigens that triggers animmune response that produce a α-SNAP-25 antibody that can bind anepitope comprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product can beuseful as a SNAP-25 antigen, including, without limitation, a SNAP-25antigen derived from a naturally occurring SNAP-25, a SNAP-25 antigenderived from a non-naturally occurring SNAP-25, and a SNAP-25 antigencomprising an immunoreactive fragment of the SNAP-25, the SNAP-25 from anaturally occurring SNAP-25 or a non-naturally occurring SNAP-25.SNAP-25 antigens useful for producing α-SNAP-25 antibodies that can bindan epitope comprising a carboxyl-terminus at the P₁ residue from theBoNT/A cleavage site scissile bond from a SNAP-25 cleavage productinclude, without limitation, SNAP-25 antigens comprising a SNAP-25peptide having a carboxylated C-terminal glutamine linked to a carrierpeptide, including, without limitation SEQ ID NO: 38. Other compositionsuseful for making α-SNAP-25 antibodies that can bind an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product include,without limitation, a composition comprising a carrier linked to aflexible linker linked to a SNAP-25 antigen a carboxylated C-terminalglutamine, wherein the flexible linker intervenes between the SNAP-25antigen and the carrier. It is envisioned that any and all adjuvants canbe useful in such a composition, including, without limitation,polyethylene glycol (PEG), monomethoxypolyethylene glycol (mPEG),polyvinyl alcohol (PVA), complete and incomplete Freund's adjuvant.

Another aspect disclosed in the present specification provides methodsof producing an α-SNAP-25 antibody that can bind an epitope comprising acarboxyl-terminus at theP_(1 residue from the BoNT/A cleavage site scissile bond from a SNAP-)25cleavage product. Aspects of this method comprise the steps of (a)administering to an animal a composition disclosed in the presentspecification; (b) collecting from the animal a sample containing anα-SNAP-25 antibody or α-SNAP-25 antibody-producing cell; and (c)isolating the α-SNAP-25 antibody from the sample. The methods disclosedare useful for making either α-SNAP-25 monoclonal antibodies that canbind an epitope comprising a carboxyl-terminus glutamine from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product or α-SNAP-25polyclonal antibodies that can bind an epitope comprising acarboxyl-terminus glutamine from the BoNT/A cleavage site scissile bondfrom a SNAP-25 cleavage product.

Still another aspect disclosed in the present specification providesα-SNAP-25 antibodies that can bind an epitope comprising acarboxyl-terminus at the P₁ residue from the BoNT/A cleavage sitescissile bond from a SNAP-25 cleavage product. Such α-SNAP-25 antibodiesinclude both naturally-occurring and non-naturally-occurring antibodies,as well as, monoclonal α-SNAP-25 antibodies or polyclonal α-SNAP-25antibodies. Monoclonal α-SNAP-25 antibodies useful as α-SNAP-25antibodies that bind an epitope comprising a carboxyl-terminus at the P₁residue from the BoNT/A cleavage site scissile bond from a SNAP-25cleavage product, include, without limitation, the monoclonal α-SNAP-25antibodies produced from hybridoma cell lines 1D3B8, 2C9B10, 2E2A6,3C1A5 and 3C3E2.

Yet another aspect disclosed in the present specification providesmethods of detecting BoNT/A activity. Aspects of this method comprisethe steps of (a) treating a cell from an established cell line with asample comprising a BoNT/A, wherein the cell from an established cellline is susceptible to BoNT/A intoxication; (b) isolating from thetreated cell a SNAP-25 component comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond; (c) contacting the SNAP-25 component with an α-SNAP-25antibody that can bind an epitope comprising a carboxyl-terminus at theP₁ residue from the BoNT/A cleavage site scissile bond from a SNAP-25cleavage product; and (d) detecting the presence of an antibody-antigencomplex comprising the α-SNAP-25 antibody and the SNAP-25 cleavageproduct; wherein detection by the antibody-antigen complex is indicativeof BoNT/A activity. The α-SNAP-25 antibody of step c can optionally belinked to a solid phase support.

Yet another aspect disclosed in the present specification providesmethods of detecting BoNT/A activity. Aspects of this method comprisethe steps of (a) treating a cell from an established cell line with asample comprising a BoNT/A, wherein the cell from an established cellline can uptake a BoNT/A; (b) isolating from the treated cell a SNAP-25component comprising a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond; (c) contacting theSNAP-25 component with an α-SNAP-25 antibody that can bind an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product; and (d)detecting the presence of an antibody-antigen complex comprising theα-SNAP-25 antibody and the SNAP-25 cleavage product; wherein detectionby the antibody-antigen complex is indicative of BoNT/A activity. Theα-SNAP-25 antibody of step c can optionally be linked to a solid phasesupport.

A further aspect disclosed in the present specification provides methodsof determining BoNT/A immunoresistance in a mammal. Aspects of thismethod comprise the steps of (a) adding a BoNT/A to a test sampleobtained from a mammal being tested for the presence or absence ofα-BoNT/A neutralizing antibodies; (b) treating a cell from anestablished cell line with the test sample, wherein the cell from anestablished cell line is susceptible to BoNT/A intoxication; (c)isolating from the treated cells a SNAP-25 component comprising aSNAP-25 cleavage product having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond; (d) contacting the SNAP-25component with an α-SNAP-25 antibody that can bind an epitope comprisinga carboxyl-terminus at the P₁ residue from the BoNT/A cleavage sitescissile bond from a SNAP-25 cleavage product; (e) detecting thepresence of an antibody-antigen complex comprising the α-SNAP-25antibody and the SNAP-25 cleavage product; (f) repeating steps a-e witha negative control sample instead of a test sample; and (g) comparingthe amount of antibody-antigen complex detected in step (e) to theamount of antibody-antigen complex detected in step (f), whereindetection of a lower amount of antibody-antigen complex detected in step(e) relative to the amount of antibody-antigen complex detected in step(f) is indicative of the presence of α-BoNT/A neutralizing antibodies.The α-SNAP-25 antibody of step d can optionally be linked to a solidphase support. The control sample in step f can also include a positivecontrol sample, in addition to the negative control sample.

Clostridia toxins produced by Clostridium botulinum, Clostridium tetani,Clostridium baratii and Clostridium butyricum are the most widely usedin therapeutic and cosmetic treatments of humans and other mammals.Strains of C. botulinum produce seven antigenically-distinct serotypesof botulinum toxins (BoNTs), which have been identified by investigatingbotulism outbreaks in man (BoNT/A, BoNT/B, BoNT/E and BoNT/F), animals(BoNT/C1 and BoNT/D), or isolated from soil (BoNT/G). While all sevenbotulinum toxin serotypes have similar structure and biologicalproperties, each also displays heterogeneous characteristics, such as,e.g., different pharmacological properties. In contrast, tetanus toxin(TeNT) is produced by a uniform group of C. tetani. Two other species ofClostridia, C. baratii and C. butyricum, also produce toxins similar toBoNT/F and BoNT/E, respectively.

Clostridial toxins are each translated as a single chain polypeptide ofapproximately 150 kDa that is subsequently cleaved by proteolyticscission within a disulfide loop by a naturally-occurring protease, suchas, e.g., an endogenous Clostridial toxin protease or anaturally-occurring protease produced in the environment. Thisposttranslational processing yields a di-chain molecule comprising anapproximately 50 kDa light chain (LC) and an approximately 100 kDa heavychain (HC) held together by a single disulfide bond and noncovalentinteractions. Each mature di-chain molecule comprises three functionallydistinct domains: 1) an enzymatic domain located in the LC that includesa metalloprotease region containing a zinc-dependent endopeptidaseactivity which specifically targets core components of theneurotransmitter release apparatus; 2) a translocation domain containedwithin the amino-terminal half of the HC (H_(N)) that facilitatesrelease of the LC from intracellular vesicles into the cytoplasm of thetarget cell; and 3) a binding domain found within the carboxyl-terminalhalf of the HC (H_(C)) that determines the binding activity and bindingspecificity of the toxin to the receptor complex located at the surfaceof the target cell.

The binding, translocation and enzymatic activity of these threefunctional domains are all necessary for toxicity. While all details ofthis process are not yet precisely known, the overall cellularintoxication mechanism whereby Clostridial toxins enter a neuron andinhibit neurotransmitter release is similar, regardless of serotype orsubtype. Although the applicants have no wish to be limited by thefollowing description, the intoxication mechanism can be described ascomprising at least four steps: 1) receptor binding, 2) complexinternalization, 3) light chain translocation, and 4) enzymatic targetmodification (FIGS. 1A-1B). The process is initiated when the HC domainof a Clostridial toxin binds to a toxin-specific receptor system locatedon the plasma membrane surface of a target cell. The binding specificityof a receptor complex is thought to be achieved, in part, by specificcombinations of gangliosides and protein receptors that appear todistinctly comprise each Clostridial toxin receptor complex. Once bound,the toxin/receptor complexes are internalized by endocytosis and theinternalized vesicles are sorted to specific intracellular routes. Thetranslocation step appears to be triggered by the acidification of thevesicle compartment. This process seems to initiate importantpH-dependent structural rearrangements that increase hydrophobicity,promote pore formation, and facilitate separation of the heavy and lightchains of the toxin. Once separated, the light chain endopeptidase ofthe toxin is released from the intracellular vesicle into the cytosolwhere it appears to specifically target core components of theneurotransmitter release apparatus. These core proteins,vesicle-associated membrane protein (VAMP)/synaptobrevin,synaptosomal-associated protein of 25 kDa (SNAP-25) and Syntaxin, arenecessary for synaptic vesicle docking and fusion at the nerve terminaland constitute members of the soluble N-ethylmaleimide-sensitivefactor-attachment protein-receptor (SNARE) family. BoNT/A and BoNT/Ecleave SNAP-25 in the carboxyl terminal region, releasing a nine ortwenty six amino acid fragment, respectively, and BoNT/C1 also cleavesSNAP-25 near the carboxyl terminus releasing an eight amino acidfragment. The botulinum serotypes BoNT/B, BoNT/D, BoNT/F and BoNT/G, andtetanus toxin, act on the conserved central portion of VAMP, and releasethe amino terminal portion of VAMP into the cytosol. BoNT/C1 cleavessyntaxin at a single site near the cytosolic membrane surface. Theselective proteolysis of synaptic SNAREs accounts for the block ofneurotransmitter release caused by Clostridial toxins in vivo. The SNAREprotein targets of Clostridial toxins are common to exocytosis in avariety of non-neuronal types; in these cells, as in neurons, lightchain peptidase activity inhibits exocytosis, see, e.g., Yann Humeau etal., How Botulinum and Tetanus Neurotoxins Block NeurotransmitterRelease, 82(5) Biochimie. 427-446 (2000); Kathryn Turton et al.,Botulinum and Tetanus Neurotoxins: Structure, Function and TherapeuticUtility, 27(11) Trends Biochem. Sci. 552-558. (2002); Giovanna Lalli etal., The Journey of Tetanus and Botulinum Neurotoxins in Neurons, 11(9)Trends Microbiol. 431-437, (2003).

Aspects of the present disclosure comprise, in part, a composition forproducing α-SNAP-25 antibodies that can bind an epitope comprising acarboxyl-terminus at the P₁ residue from the BoNT/A cleavage sitescissile bond from a SNAP-25 cleavage product. Other aspects of thepresent disclosure comprise, in part, an immune response inducingcomposition for producing α-SNAP-25 antibodies that can bind an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product. As usedherein, the term “immune response inducing composition” refers to acomposition comprising a SNAP-25 antigen which, when administered to ananimal, stimulates an immune response against the SNAP-25 antigen,thereby producing α-SNAP-25 antibodies that can bind an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product. The term“immune response” refers to any response by the immune system of ananimal to an immune response inducing composition. Exemplary immuneresponses include, but are not limited to, cellular as well as local andsystemic humoral immunity, such as, e.g., CTL responses, includingantigen-specific induction of CD8+ CTLs, helper T-cell responses,including T-cell proliferative responses and cytokine release, andB-cell responses including, e.g., an antibody producing response. Theterm “inducing an immune response” refers to administration of an immuneresponse inducing composition or a polynucleotide encoding the immuneresponse inducing composition, where an immune response is affected,i.e., stimulated, initiated or induced.

A composition comprises a SNAP-25 antigen. As used herein, the term“antigen” refers to a molecule that elicits an immune response andincludes, without limitation, peptides, polysaccharides and conjugatesof lipids, such as, e.g., lipoproteins and glycolipids. As used herein,the term “SNAP-25 antigen” refers to any antigen which has acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond that can elicit an immune response. A SNAP-25 antigen used in animmune response inducing composition must be large enough to besubstantially unique in sequence, thus reducing the possibility ofproducing antibodies that are cross reactive against antigens other thanSNAP-25. In addition, a SNAP-25 antigen used in an immune responseinducing composition must be small enough to only trigger an immuneresponse substantially against a SNAP-25 having a carboxyl-terminus atthe P₁ residue of the BoNT/A cleavage site scissile bond, thusincreasing the possibility of producing α-SNAP-25 antibodies that candistinguish a SNAP-25 having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond from a SNAP-25 lacking acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. Furthermore, it is also very desirable to generate α-SNAP-25antibodies of a single amino acid sequence in a good yield that arereproducibly selective and which bind with acceptable avidity in orderto permit the design of a highly sensitive assay.

The sequence surrounding a BoNT/A cleavage site present in SNAP-25 isdenoted as -P₅-P₄-P₃-P₂-P₁-P₁′-P₂′-P₃′-P₄′-P₅′, with P₁-P₁′ representingthe scissile bond. Upon cleavage by BoNT/A, the resulting cleavageproducts produced comprise a fragment including the P₅-P₄-P3-P2-P1sequence and a fragment including the P1′-P2′-P3′-P4′-P5′. Thus, as usedherein, the term “SNAP-25 having a carboxyl-terminus at the P₁ residueof the BoNT/A cleavage site scissile bond” refers to any SNAP-25 havingthe P₁ residue as its carboxyl-terminal amino acid. For example,Q₁₉₇-R₁₉₈ of human SNAP-25 (SEQ ID NO: 5) represents the P₁-P₁′ scissilebond for the BoNT/A cleavage site. As such, “SNAP-25 having acarboxyl-terminus glutamine of the BoNT/A cleavage site scissile bond”would be any SNAP-25 cleavage product having a glutamine at itscarboxyl-terminal amino acid where the glutamine represents Q₁₉₇ of thescissile bond. As another example, K₂₀₄-H₂₀₅ of Torpedo marmorataSNAP-25 (SEQ ID NO: 16) represents the P₁-P₁′ scissile bond for theBoNT/A cleavage site. As such, “SNAP-25 having a carboxyl-terminuslysine of the BoNT/A cleavage site scissile bond” would be any SNAP-25cleavage product having a lysine at its carboxyl-terminal amino acidwhere the lysine represents K₂₀₄ of the scissile bond.

The SNAP-25 antigen having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond from the BoNT/A cleavage site can bemodified to enhance the immunogenicity of a SNAP-25 antigen, a hapten,or any other antigenic compound that is immunogenic, non-immunogenic, orweakly immunogenic when not associated with the modification. In anaspect of this embodiment, the carboxyl-terminal P₁ residue from thescissile bond of a SNAP-25 antigen can be carboxylated. Carboxylationincreases the desired immunogenic properties of a SNAP-25 antigen in tworespects. First, because charged amino acids enhance immunogenicity,adding a COO⁻ group to the carboxyl-terminal residue will increase theoverall immunogenicity of a SNAP-25 antigen. Second, because the P₁residue of the BoNT/A cleavage site scissile bond is in a charged stateupon cleavage, adding a COO⁻ group to the carboxyl-terminal residue willbetter mimic the actual antigen that the α-SNAP-25 antibodies disclosedin the present specification are designed to bind.

In an aspect of this embodiment, the amino-terminal residue from aSNAP-25 antigen can be modified by the addition of an amino acid adaptedto attach the SNAP-25 antigen to a carrier protein, such as, e.g., akeyhole limpet hemacyanin (KLH), an ovalbumin (OVA), a thyroglobulin(THY), a bovine serum albumin (BSA), a soybean trypsin inhibitor (STI),or a multiple attachment peptide (MAP). For example, a cysteine residuecan be placed at the amino-terminus in order to conjugate the carrierprotein KLH.

Thus, an embodiment, a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can be, e.g., atleast 5, at least 6, at least 7, at least 8, at least 9, at least 10, atleast 11, at least 12, at least 13, at least 14, at least 15, at least16, at least 17, at least 18, at least 19, at least 20, at least 25, orat least 30 amino acids in length. In another embodiment, a SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond can be, e.g., at most 5, at most 6, at most7, at most 8, at most 9, at most 10, at most 11, at most 12, at most 13,at most 14, at most 15, at most 16, at most 17, at most 18, at most 19,at most 20, at most 25, or at most 30 amino acids in length. In stillanother embodiment, a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can be, e.g.,between 7-12 amino acids, between 10-15 amino acids, or between 13-18amino acids.

In another embodiment, the SNAP-25 antigen having a carboxyl-terminus atthe P₁ residue of the BoNT/A cleavage site scissile bond comprises SEQID NO: 32. In aspects of this embodiment, the SNAP-25 antigen having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond comprises SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO:36, SEQ ID NO: 37, SEQ ID NO: 147 or SEQ ID NO: 148. In a furtherembodiment, the SNAP-25 antigen having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond comprises SEQ ID NO:38.

In yet another embodiment, the SNAP-25 antigen having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond comprises SEQ ID NO: 39. In aspects of this embodiment, the SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond comprises SEQ ID NO: 40, SEQ ID NO: 41, SEQID NO: 42, SEQ ID NO: 43 or SEQ ID NO: 44. In a further embodiment, theSNAP-25 antigen having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond comprises SEQ ID NO: 45.

It is envisioned that any and all SNAP-25 antigens that triggers animmune response that produces α-SNAP-25 antibodies that bind an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product can beuseful as a SNAP-25 antigen. Thus, amino acid sequence variantscomprising SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35,SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 39, SEQ ID NO: 40, SEQ ID NO:41, SEQ ID NO: 42, SEQ ID NO: 43, SEQ ID NO: 44, SEQ ID NO: 147 or SEQID NO: 148 can be useful as a SNAP-25 antigen to trigger an immuneresponse that produces α-SNAP-25 antibodies that bind an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product. Thus, in anembodiment, a SNAP-25 antigen can substitute at least 1, at least 2, atleast 3, at least 4, or at least 5 amino acid substitutions, deletionsor additions to the SNAP-25 antigens comprising SEQ ID NO: 32, SEQ IDNO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQID NO: 39, SEQ ID NO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43,SEQ ID NO: 44, SEQ ID NO: 147 or SEQ ID NO: 148. In still anotherembodiment, a SNAP-25 antigen can have at least 70%, at least 75%, atleast 80%, at least 85%, at least 90%, or at least 95% amino acididentity to the SNAP-25 antigens comprising SEQ ID NO: 32, SEQ ID NO:33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ IDNO: 39, SEQ ID NO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, SEQID NO: 44, SEQ ID NO: 147 or SEQ ID NO: 148.

It is envisioned that one or more carriers may be linked to a SNAP-25antigen in order to enhance the immunogenicity of a SNAP-25 antigen thatis immunogenic, non-immunogenic, or weakly immunogenic when notassociated with the carrier. Non-limiting examples, include, e.g., akeyhole limpet hemacyanin (KLH), an ovalbumin (OVA), a thyroglobulin(THY), a bovine serum albumin (BSA), a soybean trypsin inhibitor (STI),or a multiple attachment peptide (MAP). As is well known in the art, anon-antigenic or weakly antigenic antigen can be made antigenic bycoupling the antigen to a carrier. Various other carrier and methods forcoupling an antigen to a carrier are well known in the art. See, e.g.,Harlow and Lane, supra, 1998a; Harlow and Lane, supra, 1998b; and DavidW. Waggoner, Jr. et al., Immunogenicity-enhancing carriers andcompositions thereof and methods of using the same, U.S. PatentPublication No. 20040057958 (Mar. 25, 2004). An epitope can also begenerated by expressing the epitope as a fusion protein. Methods forexpressing polypeptide fusions are well known to those skilled in theart as described, for example, in Ausubel et al., Current Protocols inMolecular Biology (Supplement 47), John Wley & Sons, New York (1999). Asthe carboxyl-terminal end of the SNAP-25 antigen must be the P₁ residueof the BoNT/A cleavage site scissile bond, a carrier must be linked tothe amino end of the SNAP-25 antigen.

It is envisioned that one or more flexible spacers may be linked to aSNAP-25 antigen in order to enhance the immunogenicity of a SNAP-25antigen that is immunogenic, non-immunogenic, or weakly immunogenic whennot associated with the flexible linkers. A flexible spacer increasesthe overall peptide length of the SNAP-25 antigen and providesflexibility, thereby facilitating the proper presentation of the SNAP-25antigen to the immune cells. As a non-limiting example, a compositioncan comprise a SNAP-25 antigen linked to one or more flexible spacers intandem to better present SNAP-25 antigen to immune cells, therebyfacilitating the immune response.

A flexible space comprising a peptide is at least one amino acid inlength and comprises non-charged amino acids with small side-chain Rgroups, such as, e.g., glycine, alanine, valine, leucine or serine.Thus, in an embodiment a flexible spacer can be, e.g., at least 1, atleast 2, at least 3, at least 4, at least 5, at least 6, at least 7, atleast 8, at least 9, or at least 10 amino acids in length. In anotherembodiment, a flexible spacer can be, e.g., at least 1, at most 2, atmost 3, at most 4, at most 5, at most 6, at most 7, at most 8, at most9, or at most 10 amino acids in length. In still another embodiment, aflexible spacer can be, e.g., between 1-3 amino acids, between 2-4 aminoacids, between 3-5 amino acids, between 4-6 amino acids, or between 5-7amino acids. Non-limiting examples of a flexible spacer include, e.g., aG-spacers such as GGG, GGGG (SEQ ID NO: 55), and GGGGS (SEQ ID NO: 56)or an A-spacers such as AAA, AAAA (SEQ ID NO: 57) and AAAAV (SEQ ID NO:58). A flexible spacer is linked in-frame to the SNAP-25 antigen as afusion protein.

As discussed above, a flexible spacer is used, in part, to increase theoverall peptide length of the SNAP-25 antigen. For example, a 5-10 aminoacid SNAP-25 antigen can have its overall length increased by linking a3-5 amino acid flexible space to the amino-end of the SNAP-25 antigen.As another example, a 5-10 amino acid SNAP-25 antigen can have itsoverall length increased by linking a 4-6 amino acid flexible space tothe amino-end of the SNAP-25 antigen. As another example, a 5-10 aminoacid SNAP-25 antigen can have its overall length increased by linking a7-10 amino acid flexible space to the amino-end of the SNAP-25 antigen.As another example, a 7-12 amino acid SNAP-25 antigen can have itsoverall length increased by linking a 1-3 amino acid flexible space tothe amino-end of the SNAP-25 antigen. As another example, a 7-12 aminoacid SNAP-25 antigen can have its overall length increased by linking a4-6 amino acid flexible space to the amino-end of the SNAP-25 antigen.The increased length provided by the flexible spacer allows for theselection of a small sized SNAP-25 antigen, thereby increasing thelikelihood that the SNAP-25 antigen will only trigger an immune responsesubstantially against a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond, thus increasing thepossibility of producing α-SNAP-25 antibodies that can distinguish aSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond from a SNAP-25 lacking a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond.

It is envisioned that compositions disclosed in the presentspecification can optionally comprise a SNAP-25 antigen disclosed in thepresent specification and one or more adjuvants. As used herein, theterm “adjuvant” when used in reference to a SNAP-25 composition refersto any substance or mixture of substances that increases or diversifiesthe immune response to a SNAP-25 antigen. An adjuvant can, for example,serve to reduce the number of immunizations or the amount of antigenrequired for protective immunization. The use of adjuvants in an immuneresponse inducing composition is well known. The main objective of theseadjuvants is to allow an increase in the immune response. Non-limitingadjuvants include, e.g., liposomes, oily phases, including, withoutlimitation, the Freund type of adjuvants, such as, e.g., Freund'scomplete adjuvant (FCA); Freund's incomplete adjuvant (FIA); sapogeninglycosides, such as, e.g., saponins; carbopol;N-acetylmuramyl-L-alanyl-D-isoglutamine (commonly known as muramyldipeptide or “MDP”); and lipopolysaccharide (LPS). Such adjuvants aregenerally used in the form of an emulsion with an aqueous phase, or,more commonly, may consist of water-insoluble inorganic salts. Theseinorganic salts may consist, for example, of aluminum hydroxide, zincsulfate, colloidal iron hydroxide, calcium phosphate or calciumchloride. Aluminum hydroxide (Al(OH)₃) is a commonly used adjuvant.Currently, the only FDA-approved adjuvant for use in humans is aluminumsalts (Alum) which are used to “depot” antigens by precipitation of theantigens. Adjuvants provided above are merely exemplary. In fact, anyadjuvant may be used in a SNAP-25 composition disclosed in the presentspecification as long as the adjuvant satisfies the requisitecharacteristics for inducing an immune response.

A carrier disclosed in the present specification may also act as anadjuvant. Specific adjuvants and methods of making and using aredescribed in, e.g., Gupta et al. Vaccine, 11: 993-306, 1993; Arnon, R.(Ed.) Synthetic Vaccines 1:83-92, CRC Press, Inc., Boca Raton, Fla.,1987; and David W. Waggoner, Jr. et al., Immunogenicity-EnhancingCarriers and Compositions Thereof and Methods of Using the Same, U.S.Patent Publication No. 20040057958 (Mar. 25, 2004). Additional adjuvantsinclude any compound described in Chapter 7 (pp 141-227) of “VaccineDesign, The Subunit and Adjuvant Approach” (eds. Powell, M. F. andNewman, M. J.) Pharmaceutical Biotechnology, Volume 6, Plenum Press (NewYork). Examples from this compendium include Muramyl Dipeptide (MDP) andMontanide 720. Molecules such as Poly lnosine:Cytosine (Poly I:C) orplasmid DNA containing CpG motifs can also be administered as adjuvantsin combination with antigens encapsulated in microparticles. In anotherexample, the adjuvant is an agent that facilitates entry of theantigenic compound into the cytoplasm of a cell such as listeriolysin,streptolysin or a mixture thereof.

Thus, in an embodiment, a SNAP-25 composition comprises a SNAP-25antigen having a carboxylated carboxyl-terminal glutamine linked to acarrier peptide. In aspects of this embodiment, a SNAP-25 antigen havinga carboxylated carboxyl-terminal glutamine comprises SEQ ID NO: 32, SEQID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37,SEQ ID NO: 147 or SEQ ID NO: 148. In another aspect of this embodiment,a SNAP-25 antigen comprises SEQ ID NO: 38. In aspects of thisembodiment, the carrier peptide is a keyhole limpet hemacyanin (KLH), anovalbumin (OVA), a thyroglobulin (THY), a bovine serum albumin (BSA), asoybean trypsin inhibitor (STI) or a multiple attachment peptide (MAP).

In another embodiment, a SNAP-25 composition comprises a SNAP-25 antigenhaving a carboxylated carboxyl-terminal lysine linked to a carrierpeptide. In aspects of this embodiment, SNAP-25 antigen having acarboxylated carboxyl-terminal lysine comprises SEQ ID NO: 39, SEQ IDNO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43 or SEQ ID NO: 44. Inanother aspect of this embodiment, a SNAP-25 antigen comprises SEQ IDNO: 45. In aspects of this embodiment, the carrier peptide is a keyholelimpet hemacyanin (KLH), an ovalbumin (OVA), a thyroglobulin (THY), abovine serum albumin (BSA), a soybean trypsin inhibitor (STI) or amultiple attachment peptide (MAP).

In yet another embodiment, a SNAP-25 composition comprises a SNAP-25antigen having a carboxylated C-terminal glutamine linked to one or moreflexible linkers and a carrier peptide wherein the flexible linkersintervene between the SNAP-25 antigen and the carrier peptide. Inaspects of this embodiment, SNAP-25 antigen having a carboxylatedcarboxyl-terminal glutamine comprises SEQ ID NO: 32, SEQ ID NO: 33, SEQID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 147or SEQ ID NO: 148. In another embodiment, a SNAP-25 antigen comprisesSEQ ID NO: 46. In aspects of this embodiment, the carrier peptide is akeyhole limpet hemacyanin (KLH), an ovalbumin (OVA), a thyroglobulin(THY), a bovine serum albumin (BSA), a soybean trypsin inhibitor (STI)or a multiple attachment peptide (MAP). In aspects of this embodiment,the flexible linker is a G-spacer or an A-spacer.

In still another embodiment, a SNAP-25 composition comprises a SNAP-25antigen having a carboxylated C-terminal lysine linked to a flexiblelinker and a carrier peptide wherein the flexible linker intervenesbetween the SNAP-25 antigen and the carrier peptide. In aspects of thisembodiment, SNAP-25 antigen having a carboxylated carboxyl-terminallysine comprises SEQ ID NO: 39, SEQ ID NO: 40, SEQ ID NO: 41, SEQ ID NO:42, SEQ ID NO: 43 or SEQ ID NO: 44. In another aspect of thisembodiment, a SNAP-25 antigen comprises SEQ ID NO: 47. In aspects ofthis embodiment, the carrier peptide is a keyhole limpet hemacyanin(KLH), an ovalbumin (OVA), a thyroglobulin (THY), a bovine serum albumin(BSA), a soybean trypsin inhibitor (STI) or a multiple attachmentpeptide (MAP). In aspects of this embodiment, the flexible linker is aG-spacer or an A-spacer.

Aspects of the present disclosure comprise, in part, a method forproducing α-SNAP-25 antibodies that bind an epitope comprising acarboxyl-terminus at the P₁ residue from the BoNT/A cleavage sitescissile bond from a SNAP-25 cleavage product. An α-SNAP-25 antibodythat binds an epitope comprising a carboxyl-terminus at the P₁ residuefrom the BoNT/A cleavage site scissile bond from a SNAP-25 cleavageproduct can be produced by a wide variety of methods that are well knownin the art. Specific protocols for making and using antibodies as wellas detecting, and measuring antibody binding specificity, bindingaffinity and binding avidity are known in the art. See, e.g.,ANTIBODIES: A LABORATORY MANUAL (Edward Harlow & David Lane, eds., ColdSpring Harbor Laboratory Press, 2^(nd) ed. 1998a); and USING ANTIBODIES:A LABORATORY MANUAL: PORTABLE PROTOCOL No. I (Edward Harlow & DavidLane, Cold Spring Harbor Laboratory Press, 1998b); Molecular Cloning, ALaboratory Manual, 2001; and Current Protocols in Molecular Biology,2004; David Anderson et al., Therapeutic Polypeptides, Nucleic AcidsEncoding Same, and Methods of Use, U.S. Pat. No. 7,034,132 (Apr. 25,2005); and Beatriz M. Carreno et al., Antibodies Against CTLA4, U.S.Pat. No. 7,034,121 (Apr. 25, 2006).

As a non-limiting example, α-SNAP-25 polyclonal antibodies that bind anepitope comprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product can beproduced by injecting an animal, such as, e.g., a rabbit, a goat, amouse or another mammal, with one or more injections of a compositiondisclosed in the present specification. As another non-limiting example,α-SNAP-25 polyclonal antibodies that bind an epitope comprising acarboxyl-terminus at the P₁ residue from the BoNT/A cleavage sitescissile bond from a SNAP-25 cleavage product can be produced byinjecting an egg, such as, e.g., a chicken egg, with one or moreinjections of a composition disclosed in the present specification. Theantibody titer in the immunized animal can be monitored over time bystandard techniques, such as with an enzyme linked immunosorbent assay(ELISA) using immobilized antigen or a cell-based activity assay. Ifdesired, polyclonal antibodies for an α-SNAP-25 antibody that binds anepitope comprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product can beisolated from the mammal (e.g., from the blood) and further purified bywell known techniques, such as protein A affinity chromatography toobtain the IgG fraction, or by affinity purification against the peptideused for producing the antibodies.

As another non-limiting example, α-SNAP-25 monoclonal antibody thatbinds an epitope comprising a carboxyl-terminus at the P₁ residue fromthe BoNT/A cleavage site scissile bond from a SNAP-25 cleavage productcan be produced using a hybridoma method. See e.g., Chapter 6 MonoclonalAntibodies, pp. 196-244, Harlow & Lane, supra, 1998a; and Chapter 7Growing Hybridomas, pp. 245-282, Harlow & Lane, supra, 1998a; andGoding, pp. 59-103, Monoclonal Antibodies: Principles and Practice,Academic Press, (1986). In this method, a host animal, such as, e.g., amouse, a hamster, or another appropriate host animal, is typicallyexposed to one or more injections of a SNAP-25 antigen disclosed in thepresent specification to elicit lymphocytes that produce or are capableof producing α-SNAP-25 antibodies that will specifically bind to aSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond. The antibody titer in the immunized animalcan be monitored over time by standard techniques, such as with anenzyme linked immunosorbent assay (ELISA) using immobilized antigen or acell-based activity assay. Alternatively, the lymphocytes can beimmunized in vitro using a suitable cell culture line. At an appropriatetime after immunization, e.g., when the antibody titers are highest,antibody-producing cells are isolated from the animal. Generally, eitherperipheral blood lymphocytes are used, if cells of human origin aredesired, or spleen cells or lymph node cells are used, if non-humanmammalian sources are desired. The isolated antibody-producing cells arefused with an immortal cell line using a suitable fusing agent, such aspolyethylene glycol, to form a hybridoma cell. Immortalized cell linesare usually transformed mammalian cells, particularly myeloma cells ofrodent, bovine and human origin. Typically, a murine myeloma cell lineis fused with splenocytes harvested from an appropriately immunizedmouse to produce the hybridoma. Preferred immortal cell lines are mousemyeloma cell lines that are sensitive to culture medium containinghypoxanthine, aminopterin and thymidine (HAT). Any of a number ofmyeloma cell lines can be used as a fusion partner according to standardtechniques, e.g., the P3-NS1/1-Ag4-1, P3-x63-Ag8.653 or Sp2/O—Ag14myeloma lines. Hybridoma cells resulting from the fusion are thenselected using HAT medium, which kills unfused and unproductively fusedmyeloma cells (unfused splenocytes die after several days in culturebecause they are not transformed). The culture medium in which thehybridoma cells are grown can then be assayed for the presence ofα-SNAP-25 monoclonal antibodies that bind an epitope comprising acarboxyl-terminus at the P₁ residue from the BoNT/A cleavage sitescissile bond from a SNAP-25 cleavage product. For example, hybridomasupernatants can be screened using α-SNAP-25 positive media in animmunoprecipitation assay, in vitro binding assay, such as, e.g., aradioimmunoassay (RIA) or an enzyme-linked immunoabsorbent assay(ELISA), or in a cell-based activity assay. Such techniques and assaysare known in the art. See e.g., Chapter 11 Immunoprecipitation, pp.421-470, Harlow & Lane, supra, 1998a; Chapter 12 Immunoblotting, pp.471-510, Harlow & Lane, supra, 1998a; Chapter 14 Immunoassays, pp.553-612, Harlow & Lane, supra, 1998a. Additional studies can then bedone to determine whether the antibody is also unreactive to a SNAP-25lacking a carboxyl-terminus at the P₁ residue of the BoNT/A cleavagesite scissile bond. The binding affinity of an α-SNAP-25 monoclonalantibody can also be determined, e.g., by Scatchard analysis. See, e.g.,Peter J. Munson and David Rodbard, Ligand: A Versatile ComputerizedApproach For Characterization of Ligand-Binding Systems, 107(1) Anal.Biochem. 220-239 (1980). After the desired hybridoma cells areidentified, limiting dilution procedures are used to isolate clonesoriginating from a single cell until a clonal cell line expressing thedesired monoclonal antibody is obtained. Those antibodies sufficientlyselective for a SNAP-25 having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond and bind with sufficiently highavidity are chosen for further characterization and study.

Another alternative for preparing an α-SNAP-25 monoclonal antibody thatbinds an epitope comprising a carboxyl-terminus at the P₁ residue fromthe BoNT/A cleavage site scissile bond from a SNAP-25 cleavage productis by screening a recombinant combinatorial immunoglobulin library, suchas, e.g., an antibody phage display library, with a SNAP-25 peptide andisolate immunoglobulin library members that bind a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. Kits for generating and screening phage display libraries arecommercially available, such as, e.g., the Recombinant Phage AntibodySystem (Amersham GE Healthcare, Piscataway, N.J.); and the SurfZAP™Phage Display Kit (Stratagene, La Jolla, Calif.). Additionally, examplesof methods and reagents useful in generating and screening antibodydisplay library can be found in, for example, Ladner et al. U.S. Pat.No. 5,223,409; Borrebaeck et al. U.S. Pat. No. 5,712,089; Griffiths etal. U.S. Pat. No. 5,885,793; Griffiths et al. U.S. Pat. No. 5,962,255;McCafferty et al. U.S. Pat. No. 5,969,108; Griffiths et al. U.S. Pat.No. 6,010,884; Jespers et al. U.S. Pat. No. 6,017,732; Borrebaeck et al.U.S. Pat. No. 6,027,930; Johnson et al. U.S. Pat. No. 6,140,471;McCafferty et al. U.S. Pat. No. 6,172,197, each of which is herebyincorporated by reference in its entirety.

Aspects of the present disclosure comprise, in part, collecting a samplecontaining an α-SNAP-25 antibody or α-SNAP-25 antibody-producing cells.As used herein, the term “sample containing an α-SNAP-25 antibody orα-SNAP-25 antibody-producing cell” refers to any biological matter thatcontains or potentially contains at least one an α-SNAP-25 antibody thatthat bind an epitope comprising a carboxyl-terminus at the P₁ residuefrom the BoNT/A cleavage site scissile bond from a SNAP-25 cleavageproduct. It is envisioned that any and all samples that can contain anα-SNAP-25 antibody that binds an epitope comprising a carboxyl-terminusat the P₁ residue from the BoNT/A cleavage site scissile bond from aSNAP-25 cleavage product can be used in this method, including, withoutlimitation, blood, plasma, serum and lymph fluid. It is also envisionedthat any cell capable of producing an α-SNAP-25 antibody that binds anepitope comprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product can be usedin this method, including, without limitation, a CD8 cells, a CTL cell,a helper T-cell and a B-cell. A variety of well known methods can beused for collecting from an individual a sample containing the α-SNAP-25antibody or α-SNAP-25 antibody-producing cell, see, e.g., Harlow & Lane,supra, 1998a; and Harlow & Lane, supra, 1998b. Similarly, a variety ofwell known methods can be used for processing a sample to isolate anα-SNAP-25 antibody that binds an epitope comprising a carboxyl-terminusat the P₁ residue from the BoNT/A cleavage site scissile bond from aSNAP-25 cleavage product. A procedure for collecting a sample can beselected based on the type of antibody to be isolated. As a non-limitingexample, when isolating an α-SNAP-25 polyclonal antibodies that bind anepitope comprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product, anappropriate sample can be a blood sample containing such α-SNAP-25antibodies, whereas when isolating an α-SNAP-25 monoclonal antibodiesthat bind an epitope comprising a carboxyl-terminus at the P₁ residuefrom the BoNT/A cleavage site scissile bond from a SNAP-25 cleavageproduct, an appropriate sample can be an α-SNAP-25 antibody-producingcell such as a spleen cell or hybridoma.

Aspects of the present disclosure comprise, in part, isolating anα-SNAP-25 antibody that binds an epitope comprising a carboxyl-terminusat the P₁ residue from the BoNT/A cleavage site scissile bond from aSNAP-25 cleavage product from the sample. Methods of isolating an suchα-SNAP-25 antibodies, such as, e.g., α-SNAP-25 polyclonal antibodiesthat bind an epitope comprising a carboxyl-terminus at the P₁ residuefrom the BoNT/A cleavage site scissile bond from a SNAP-25 cleavageproduct or α-SNAP-25 monoclonal antibodies that bind an epitopecomprising a carboxyl-terminus at the P1 residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product are wellknown to those skilled in the art. See, e.g., Harlow and Lane, supra,1998a; and Harlow and Lane, supra, 1998b. For example, such α-SNAP-25polyclonal antibodies can be isolated from the sample by well knowntechniques, such as, e.g., affinity chromatography using protein A orprotein G, which provide primarily the IgG fraction of immune serum.Subsequently, or alternatively, a specific SNAP-25 antigen can beimmobilized on a column or magnetic beads to purify the α-SNAP-25polyclonal antibodies that bind an epitope comprising acarboxyl-terminus at the P₁ residue from the BoNT/A cleavage sitescissile bond from a SNAP-25 cleavage product by immunoaffinitychromatography. An α-SNAP-25 monoclonal antibody that binds an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product can beisolated from the culture medium or ascites fluid by conventionalimmunoglobulin purification procedures such as, e.g., proteinA-Sepharose, hydroxylapatite chromatography, gel electrophoresis,dialysis, or affinity chromatography.

Thus, in an embodiment, a method of producing an α-SNAP-25 antibody thatbinds an epitope comprising a carboxyl-terminus at the P₁ residue fromthe BoNT/A cleavage site scissile bond from a SNAP-25 cleavage productcomprises the steps (a) administering to an animal a compositioncomprising a SNAP-25 antigen having a carboxylated C-terminal glutaminelinked to a carrier peptide; (b) collecting from the animal a samplecontaining an α-SNAP-25 antibody or α-SNAP-25 antibody-producing cell;and (c) isolating the α-SNAP-25 antibody component from the sample. Inan aspect of this embodiment, the α-SNAP-25 antibody that binds anepitope comprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product is apolyclonal antibody. In another aspect of this embodiment, an α-SNAP-25antibody that binds an epitope comprising a carboxyl-terminus at the P₁residue from the BoNT/A cleavage site scissile bond from a SNAP-25cleavage product is a monoclonal antibody. In a further aspect of thisembodiment, an α-SNAP-25 monoclonal antibody that binds an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product produced isan IgG subtype. In other aspects of this embodiment, SNAP-25 compositionfurther comprises an adjuvant, such as, e.g., polyethylene glycol (PEG),monomethoxypolyethylene glycol (mPEG), or polyvinyl alcohol (PVA).

In another embodiment, a method of producing α-SNAP-25 antibodies thatbind an epitope comprising a carboxyl-terminus at the P₁ residue fromthe BoNT/A cleavage site scissile bond from a SNAP-25 cleavage productcomprises the steps (a) administering to an animal a compositioncomprising a SNAP-25 peptide having a carboxylated C-terminal glutaminelinked to a flexible linker and a carrier peptide wherein the flexiblelinker intervenes between the SNAP-25 peptide and the carrier peptide;(b) collecting from the animal a sample containing an α-SNAP-25 antibodyor α-SNAP-25 antibody-producing cell; and (c) isolating the α-SNAP-25antibody from the sample. In an aspect of this embodiment, the α-SNAP-25antibodies that bind an epitope comprising a carboxyl-terminus at the P1residue from the BoNT/A cleavage site scissile bond from a SNAP-25cleavage product is a polyclonal antibody. In another aspect of thisembodiment, α-SNAP-25 antibodies that bind an epitope comprising acarboxyl-terminus at the P1 residue from the BoNT/A cleavage sitescissile bond from a SNAP-25 cleavage product is a monoclonal antibody.In a further aspect of this embodiment, an α-SNAP-25 monoclonal antibodythat binds an epitope comprising a carboxyl-terminus at the P1 residuefrom the BoNT/A cleavage site scissile bond from a SNAP-25 cleavageproduct produced in an IgG subtype. In other aspects of this embodiment,SNAP-25 composition further comprises an adjuvant, such as, e.g.,polyethylene glycol (PEG), monomethoxypolyethylene glycol (mPEG), orpolyvinyl alcohol (PVA).

Aspects of the present disclosure comprise, in part, an isolatedα-SNAP-25 antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. As used herein, the term “isolated” refers to separating amolecule from its natural environment by the use of human intervention.As used herein, the term “antibody” refers to a molecule generated by animmune system that was made in response to a particular antigen thatspecifically binds to that antigen, and includes both naturallyoccurring antibodies and non-naturally occurring antibodies. As usedherein, the term “α-SNAP-25” is synomonous with “anti-SNAP-25” andrefers to an antibody that binds to a SNAP-25 antigen. For example, anantibody can be a polyclonal antibody, a monoclonal antibody, a dimer, amultimer, a multispecific antibody, a humanized antibody, a chimericantibody, bi-functional antibody, a cell-associated antibody like an Igreceptor, a linear antibody, a diabody, or a minibody, so long as thefragment exhibits the desired biological activity, and single chainderivatives of the same. An antibody can be a full-length immunoglobulinmolecule comprising the V_(H) and V_(L) domains, as well as a lightchain constant domain (C_(L)) and heavy chain constant domains, C_(H1),C_(H2) and C_(H3), or an immunologically active fragment of afull-length immunoglobulin molecule, such as, e.g., a Fab fragment, aF(ab′)₂ fragment, a Fc fragment, a Fd fragment, a Fv fragment. Anantibody can be derived from any vertebrate species (e.g., human, goat,horse, donkey, murine, rat, rabbit, or chicken), and can be of any type(e.g., IgG, IgE, IgM, IgD, and IgA), class (e.g., IgA, IgD, IgE, IgG,and IgM) or subclass (IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2). Forgeneral disclosure on the structure of naturally occurring antibodies,non-naturally occurring antibodies, and antigenic compound-bindingfragments thereof, see, e.g., Pluckthun in The Pharmacology ofMonoclonal Antibodies, vol. 113, Rosenburg and Moore eds.,Springer-Verlag, New York, pp. 269-315 (1994); Borrabeck, AntibodyEngineering, 2d ed. (Oxford University Press 1995), each of which ishereby incorporated by reference in its entirety.

Naturally-occurring antibodies are usually heterotetramericglycoproteins of about 150,000 daltons, composed of two identical light(L) chains and two identical heavy (H) chains. Each light chain islinked to a heavy chain by one covalent disulfide bond, while the numberof disulfide linkages varies among the heavy chains of differentimmunoglobulin isotypes. Each heavy and light chain also has regularlyspaced intrachain disulfide bridges. Each heavy chain has at one end avariable domain (V_(H)) followed by a number of constant domains. Eachlight chain has a variable domain at one end (V_(L)) and a constantdomain at its other end. The constant domain of the light chain isaligned with the first constant domain of the heavy chain, and thelight-chain variable domain is aligned with the variable domain of theheavy chain. Particular amino acid residues are believed to form aninterface between the light chain and heavy chain variable domains.

The complete antigen-recognition and antigen-binding site is containedwithin the variable domains of the antibody, i.e., the Fv fragment. Thisfragment includes a dimer of one heavy chain variable domain (V_(H)) andone light chain variable domain (V_(L)) in tight, non-covalentassociation. Each domain comprises four framework regions (FR), whichlargely adopting a β-sheet configuration, connected by threehypervariable regions, which form loops connecting, and in some casesform part of, the β-sheet structure. Each hypervariable region comprisesan amino acid sequence corresponding to a complementarity determiningregion (CDRs). Collectively, it the three-dimensional configuration ofthe six CDR regions that define an antigen-binding site on the surfaceof the V_(H)-V_(L) dimmer that confers antigen-binding specificity. Seee.g., Cyrus Chothia, et al., Conformations of ImmunoglobulinHypervariable Regions, Nature 342(6252): 877-883 (1989); Elvin A. Kabat,et al Sequences of Proteins of Immunological Interest, 5th Ed. PublicHealth Service, National Institutes of Health, Bethesda, Md. (1991),each of which is incorporated by reference in its entirety. The constantdomains of the antibody are not involved directly in binding an antibodyto an antigen, but exhibit various effector functions, such asparticipation of the antibody in antibody dependent cellularcytotoxicity.

A target antigen generally has one or more binding sites, also calledepitopes, which are recognized by the CDR-formed antigen-binding site.As used herein, an “epitope” is synonymous with “antigenic determinant”and refers to the site on a target antigen, such as, e.g., a peptide,polysaccharide or lipid-containing molecule, capable of specific bindingto an immunoglobulin or T-cell receptor or otherwise interacting with amolecule. Each antibody that specifically binds to a different epitopehas a different structure. Thus, one antigen may have more than onecorresponding antibody.

Polyclonal antibodies refer to a heterogeneous population of antibodymolecules that contain at least two species of antibody capable ofbinding to a particular antigen. By definition, a polyclonal antibodyincludes two different antibodies that bind to at least two differentepitopes. As used herein, the term “monoclonal antibody” or “monoclonalantibodies” refer to a substantially homogeneous population of antibodymolecules that contain only one species of antibody capable of binding aparticular antigen i.e., the individual antibodies comprising thepopulation are identical except for possible naturally occurringmutations that may be present in minor amounts. By definition, amonoclonal antibody binds to a single epitope. Monoclonal antibodies arehighly specific, being directed against a single antigenic site.Furthermore, in contrast to polyclonal antibodies, each monoclonalantibody is directed against a single determinant on the antigen. Inaddition to their specificity, the monoclonal antibodies areadvantageous in that they may be synthesized uncontaminated by otherantibodies. The modifier “monoclonal” indicates the character of theantibody as being obtained from a substantially homogeneous populationof antibodies, and is not to be construed as requiring production of theantibody by any particular method. For example, the monoclonalantibodies to be used in accordance with the present disclosure may bemade by the hybridoma method first described by Kohler et al (1975)Nature 256:495, or may be made by recombinant DNA methods (see forexample: U.S. Pat. Nos. 4,816,567; 5,807,715). The monoclonal antibodiesmay also be isolated from phage antibody libraries using the techniquesdescribed in Clackson et al (1991) Nature, 352:624-628; Marks et al(1991) J. Mol. Biol., 222:581-597; for example.

Thus, in an embodiment, an α-SNAP-25 antibody comprises a heavy chainvariable domain (V_(H)) and a light chain variable domain (V_(L)) thatselectively binds to a SNAP-25 having a carboxyl-terminus at the P1residue of the BoNT/A cleavage site scissile bond. In an aspect of thisembodiment, the heavy chain variable domain (V_(H)) is SEQ ID NO: 72,SEQ ID NO: 74, SEQ ID NO: 76, SEQ ID NO: 80, or SEQ ID NO: 82. Inanother aspect of this embodiment, the light chain variable domain(V_(L)) is SEQ ID NO: 84, SEQ ID NO: 86, SEQ ID NO: 88, SEQ ID NO: 90,or SEQ ID NO: 92.

In another embodiment, an α-SNAP-25 antibody comprises a heavy chainvariable domain (V_(H)) CDR1 region, a CDR2 region, a CDR3 region, orany combination thereof that selectively binds to a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. In an aspect of this embodiment, the heavy chain variable domain(V_(H)) CDR1 region is SEQ ID NO: 93, SEQ ID NO: 94, SEQ ID NO: 95, SEQID NO: 118, SEQ ID NO: 119, or SEQ ID NO: 120. In another aspect of thisembodiment, the heavy chain variable domain (V_(H)) CDR2 region is SEQID NO: 96, SEQ ID NO: 97, SEQ ID NO: 98, SEQ ID NO: 99, SEQ ID NO: 121,SEQ ID NO: 122, or SEQ ID NO: 123. In yet another aspect of thisembodiment, the heavy chain variable domain (V_(H)) CDR3 region is SEQID NO: 100, SEQ ID NO: 101, SEQ ID NO: 102, or SEQ ID NO: 124.

In another embodiment, an α-SNAP-25 antibody comprises a light chainvariable domain (V_(L)) CDR1 region, a CDR2 region, a CDR3 region, orany combination thereof that selectively binds to a SNAP-25 having acarboxyl-terminus at the P1 residue of the BoNT/A cleavage site scissilebond. In an aspect of this embodiment, the light chain variable domain(V_(L)) CDR1 region is SEQ ID NO: 103, SEQ ID NO: 104, SEQ ID NO: 105,SEQ ID NO: 106, SEQ ID NO: 107, SEQ ID NO: 125, SEQ ID NO: 126, SEQ IDNO: 127, SEQ ID NO: 128, or SEQ ID NO: 129. In another aspect of thisembodiment, the light chain variable domain (V_(L)) CDR2 region is SEQID NO: 108, SEQ ID NO: 109, SEQ ID NO: 110, SEQ ID NO: 111, or SEQ IDNO: 112. In yet another aspect of this embodiment, the light chainvariable domain (V_(L)) CDR3 region is SEQ ID NO: 113, SEQ ID NO: 114,SEQ ID NO: 115, SEQ ID NO: 116, or SEQ ID NO: 117.

In yet another embodiment, an α-SNAP-25 antibody specifically binds anepitope comprising a SNAP-25 having a carboxyl-terminus at the P1residue of the BoNT/A cleavage site scissile bond. In an aspect of thisembodiment, the epitope comprises SEQ ID NO: 32, SEQ ID NO: 33, SEQ IDNO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 147 orSEQ ID NO: 148. In an aspect of this embodiment, the epitope comprisesSEQ ID NO: 39, SEQ ID NO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO:43, or SEQ ID NO: 44.

As discussed above, the sequence surrounding a BoNT/A cleavage sitepresent in SNAP-25 is denoted P₅-P₄-P₃-P₂-P₁-P₁′-P₂′-P₃′-P₄′-P₅′, withP₁-P₁′ representing the scissile bond. Upon cleavage by BoNT/A, theresulting cleavage products produced comprise a fragment including theP₅-P₄-P₃-P₂-P₁ sequence and a fragment including theP₁′-P₂′-P₃′-P₄′-P₅′. As used herein, the term “α-SNAP-25 antibodies thatbind an epitope comprising a carboxyl-terminus at the P₁ residue fromthe BoNT/A cleavage site scissile bond from a SNAP-25 cleavage product”refers to α-SNAP-25 antibodies that selectively bind to any SNAP-25cleavage product fragment comprising the P₅-P₄-P₃-P₂-P₁ sequence, butnot to any SNAP-25 cleavage product fragment comprising theP₁′-P₂′-P₃′-P₄′-P₅′ sequence or to any SNAP-25 having an intact P₁-P₁′scissile bond of a BoNT/A cleavage site. As used herein, the term“α-SNAP-25₁₉₇ antibody” refers to an antibody that selectively binds toa SNAP-25 having a carboxyl-terminus P₁ residue that corresponds toglutamine 197 of SEQ ID NO: 5. As used herein, the term “α-SNAP-25₂₀₄antibody” refers to an antibody that selectively binds to a SNAP-25having a carboxyl-terminus P₁ residue that corresponds to lysine 204 ofSEQ ID NO: 16.

As used herein, the term “selectively” refers to having a unique effector influence or reacting in only one way or with only one thing. As usedherein, the term “selectively binds,” when made in reference to anantibody, refers to the discriminatory binding of the antibody to theindicated target epitope such that the antibody does not substantiallycross react with non-target epitopes. The minimal size of a peptideepitope, as defined herein, is about five amino acids, and a peptideepitope typically comprises at least 5, at least 6, at least 7, at least8, at least 9, at least 10, at least 15, or at least 20 amino acids. Apeptide epitope may be discontinuous, i.e., it comprises amino acidresidues that are not adjacent in the primary structure of the peptidebut are brought together into an epitope by way of the secondary,tertiary, or quaternary structure of the peptide. Furthermore, it isalso noted that an epitope might comprise a portion of a molecule otherthan an amino acid sequence, such as, e.g., a carbohydrate moiety, alipid moiety like lipoproteins or glycolipids, or a chemically-modifiedamino acid moiety like a phosphorylated amino acid. In aspects of thisembodiment, an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond can selectively bind a SNAP-25 epitopehaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond comprising at least 5, at least 6, at least 7, at least 8,at least 9, at least 10, at least 15, or at least 20 amino acids. Inother aspects of this embodiment, an α-SNAP-25 antibody that selectivelybinds to a SNAP-25 epitope having a carboxyl-terminus at the P₁ residueof the BoNT/A cleavage site scissile bond can selectively bind a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond comprising at most 5, at most 6, at most 7,at most 8, at most 9, at most 10, at most 15, or at most 20 amino acids.

Selective binding includes binding properties such as, e.g., bindingaffinity, binding specificity, and binding avidity. See David J. King,Applications and Engineering of Monoclonal Antibodies, pp. 240 (1998).Binding affinity refers to the length of time the antibody resides atits epitope binding site, and can be viewed as the strength with whichan antibody binds its epitope. Binding affinity can be described anantibody's equilibrium dissociation constant (KD), which is defined asthe ratio Kd/Ka at equillibrium. Where Ka is the antibody's associationrate constant and kd is the antibody's dissociation rate constant.Binding affinity is determined by both the association and thedissociation and alone neither high association or low dissociation canensure high affinity. The association rate constant (Ka), or on-rateconstant (Kon), measures the number of binding events per unit time, orthe propensity of the antibody and the antigen to associate reversiblyinto its antibody-antigen complex. The association rate constant isexpressed in M⁻¹ s⁻¹, and is symbolized as follows: [Ab]×[Ag]×Kon. Thelarger the association rate constant, the more rapidly the antibodybinds to its antigen, or the higher the binding affinity betweenantibody and antigen. The dissociation rate constant (Kd), or off-rateconstant (Koff), measures the number of dissociation events per unittime propensity of an antibody-antigen complex to separate (dissociate)reversibly into its component molecules, namely the antibody and theantigen. The dissociation rate constant is expressed in s⁻¹, and issymbolized as follows: [Ab+Ag]×Koff. The smaller the dissociation rateconstant, the more tightly bound the antibody is to its antigen, or thehigher the binding affinity between antibody and antigen. Theequilibrium dissociation constant (KD) measures the rate at which newantibody-antigen complexes formed equals the rate at whichantibody-antigen complexes dissociate at equilibrium. The equilibriumdissociation constant is expressed in M, and is defined asKoff/Kon=[Ab]×[Ag]/[Ab+Ag], where [Ab] is the molar concentration of theantibody, [Ag] is the molar concentration of the antigen, and [Ab+Ag] isthe of molar concentration of the antibody-antigen complex, where allconcentrations are of such components when the system is at equilibrium.The smaller the equilibrium dissociation constant, the more tightlybound the antibody is to its antigen, or the higher the binding affinitybetween antibody and antigen.

Thus, in an embodiment, the binding affinity of an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond can have anassociation rate constant of, e.g., less than 1×10⁵ M⁻¹ s⁻¹, less than1×10⁶ M⁻¹ s⁻¹, less than 1×10⁷ M⁻¹ s⁻¹, or less than 1×10⁸ M⁻¹ s⁻¹. Inanother embodiment, the binding affinity of an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can have anassociation rate constant of, e.g., more than 1×10⁵ M⁻¹ s⁻¹, more than1×10⁶ M⁻¹ s⁻¹, more than 1×10⁷ M⁻¹ s⁻¹, or more than 1×10⁸ M⁻¹ s⁻¹. Inother aspects, the binding affinity of an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can have anassociation rate constant between 1×10⁵ M⁻¹ s⁻¹ to 1×10⁸ M⁻¹ s⁻¹, 1×10⁶M⁻¹ s⁻¹ to 1×10⁸ M⁻¹, 1×10⁵ M⁻¹ s⁻¹ to 1×10⁷ M⁻¹ s⁻¹, or 1×10⁶ Mm⁻¹ s⁻¹to 1×10⁷ M⁻¹ s⁻¹.

In another embodiment, the binding affinity of an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond can have adisassociation rate constant of less than 1×10⁻³ s⁻¹, less than 1×10⁻⁴s⁻¹, or less than 1×10⁻⁵ s⁻¹. In other aspects of this embodiment, thebinding affinity of an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can have a disassociation rateconstant of, e.g., less than 1.0×10⁻⁴ s⁻¹, less than 2.0×10⁻⁴ s⁻¹, lessthan 3.0×10⁻⁴ s⁻¹, less than 4.0×10⁻⁴ s⁻¹, less than 5.0×10⁻⁴ s⁻¹, lessthan 6.0×10⁻⁴ s⁻¹, less than 7.0×10⁻⁴ s⁻¹, less than 8.0×10⁻⁴ s⁻¹, orless than 9.0×10⁻⁴ s⁻¹. In another embodiment, the binding affinity ofan α-SNAP-25 antibody that selectively binds to a SNAP-25 epitope havinga carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond can have a disassociation rate constant of, e.g., morethan 1×10⁻³ s⁻¹, more than 1×10⁻⁴ s⁻¹, or more than 1×10⁻⁵ s⁻¹. In otheraspects of this embodiment, the binding affinity of an α-SNAP-25antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond can have a disassociation rate constant of, e.g., more than1.0×10⁻⁴ s⁻¹, more than 2.0×10⁻⁴ s⁻¹, more than 3.0×10⁻⁴ s⁻¹, more than4.0×10⁻⁴ s⁻¹, more than 5.0×10⁻⁴ s⁻¹, more than 6.0×10⁻⁴ s⁻¹, more than7.0×10⁻⁴ s⁻¹, more than 8.0×10⁻⁴ s⁻¹, or more than 9.0×10⁻⁴ s⁻¹.

In another embodiment, the binding affinity of an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond can have anequilibrium disassociation constant of less than 0.500 nM. In aspects ofthis embodiment, the binding affinity of an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can have anequilibrium disassociation constant of, e.g., less than 0.500 nM, lessthan 0.450 nM, less than 0.400 nM, less than 0.350 nM, less than 0.300nM, less than 0.250 nM, less than 0.200 nM, less than 0.150 nM, lessthan 0.100 nM, or less than 0.050 nM. In another embodiment, the bindingaffinity of an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond can have an equilibrium disassociationconstant of more than 0.500 nM. In aspects of this embodiment, thebinding affinity of an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can have an equilibriumdisassociation constant of, e.g., more than 0.500 nM, more than 0.450nM, more than 0.400 nM, more than 0.350 nM, more than 0.300 nM, morethan 0.250 nM, more than 0.200 nM, more than 0.150 nM, more than 0.100nM, or more than 0.050 nM.

In yet another embodiment, the binding affinity of an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond can have anassociation rate constant of for the intact SNAP-25 of, e.g., less than1×10⁰ M⁻¹ s⁻¹, less than 1×10¹ M⁻¹ s⁻¹, less than 1×10² M⁻¹ s⁻¹, lessthan 1×10³ M⁻¹ s⁻¹, or less than 1×10⁴ M⁻¹ s⁻¹. In another embodiment,the binding affinity of an α-SNAP-25 antibody that selectively binds toa SNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can have an association rate constantof for the intact SNAP-25 of, e.g., at most 1×10⁰ M⁻¹ s⁻¹, at most 1×10¹M⁻¹ s⁻¹, at most 1×10² M⁻¹ s⁻¹, at most 1×10³ M⁻¹ s⁻¹, or at most 1×10⁴M⁻¹ s⁻¹.

Binding specificity is the ability of an antibody to discriminatebetween a molecule containing its epitope and a molecule that does notcontain that epitope. One way to measure binding specificity is tocompare the Kon association rate of the antibody for a moleculecontaining its epitope relative to the Kon association rate of theantibody for a molecule that does not contain that epitope. For example,comparing the association rate constant (Ka) of an α-SNAP-25 antibodyfor a SNAP-25 epitope having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond relative to a SNAP-25 notcomprising that epitope, such as, e.g., a SNAP-25 epitope lacking acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond or a SNAP-25 epitope having an intact P₁-P₁′ scissile bond of aBoNT/A cleavage site. In aspects of this embodiment, an α-SNAP-25antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond has an association rate constant (Ka) for a SNAP-25 not comprisingits epitope(s) of, e.g., less than 1×10⁰ M⁻¹ s⁻¹, less than 1×10¹ M⁻¹s⁻¹, less than 1×10² M⁻¹ s⁻¹, less than 1×10³ M⁻¹ s⁻¹ or less than 1×10⁴M⁻¹ s⁻¹. In other aspects of this embodiment, an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond has an associationrate constant (Ka) for a SNAP-25 not comprising its epitope(s) of, e.g.,at most 1×10⁰ M⁻¹ s⁻¹, at most 1×10¹ M⁻¹ s⁻¹, at most 1×10² M⁻¹ s⁻¹, atmost 1×10³ M⁻¹ s⁻¹ or at most 1×10⁴ M⁻¹ s⁻¹.

In yet aspects of this embodiment, an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond has an associationrate constant (Ka) for its epitope relative to a SNAP-25 not comprisingthat epitope of, e.g., at least 2-fold more, at least 3-fold more, atleast 4-fold more, at least 5-fold more, at least 6-fold more, at least7-fold more, at least 8-fold more, or at least 9-fold more. In furtheraspects of this embodiment, an α-SNAP-25 antibody that selectively bindsto a SNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond has an association rate constant (Ka)for its epitope relative to a SNAP-25 not comprising that epitope of,e.g., at least 10-fold more, at least 100-fold more, at least 1,000-foldmore or at least 10,000-fold more. In yet other aspects of thisembodiment, an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond has an association rate constant (Ka) forits epitope relative to a SNAP-25 not comprising that epitope of, e.g.,at most 1-fold more, at most 2-fold more, at most 3-fold more, at most4-fold more, at most 5-fold more, at most 6-fold more, at most 7-foldmore, at most 8-fold more, or at most 9-fold more. In yet other aspectsof this embodiment, an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond has an association rate constant (Ka)for its epitope relative to a SNAP-25 not comprising that epitope of,e.g., at most 10-fold more, at most 100-fold more, at most 1,000-foldmore or at most 10,000-fold more.

The binding specificity of an α-SNAP-25 antibody that selectively bindsto a SNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond can also be characterized as a ratiothat such an α-SNAP-25 antibody can discriminate its SNAP-25 epitoperelative to a SNAP-25 not comprising that epitope, such as, e.g., aSNAP-25 epitope lacking a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond or a SNAP-25 epitope having an intactP₁-P₁′ scissile bond of a BoNT/A cleavage site. In aspects of thisembodiment, an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond has a binding specificity ratio for itsSNAP-25 epitope relative to a SNAP-25 not comprising that epitope of,e.g., at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least64:1, at least 7:1, at least 8:1, at least 9:1, at least 10:1, at least15:1, at least 20:1, at least 25:1, at least 30:1, at least 35:1, or atleast 40:1. In yet other aspects of this embodiment, an α-SNAP-25antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond has a binding specificity ratio for its SNAP-25 epitope relative toa SNAP-25 lacking a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond of, e.g., at least 2:1, at least 3:1, atleast 4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, atleast 9:1, at least 10:1, at least 15:1, at least 20:1, at least 25:1,at least 30:1, at least 35:1, or at least 40:1. In still other aspectsof this embodiment, an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond has a binding specificity ratio forits SNAP-25 epitope relative to a SNAP-25 having an intake P₁-P₁′scissile bond of a BoNT/A cleavage site of, e.g., at least 2:1, at least3:1, at least 4:1, at least 5:1, at least 64:1, at least 7:1, at least8:1, at least 9:1, at least 10:1, at least 15:1, at least 20:1, at least25:1, at least 30:1, at least 35:1, or at least 40:1.

Binding avidity, also known as functional affinity, refers to the sumtotal of the functional binding strength between a multivalent antibodyand its antigen. Antibody molecules can have more than one binding site(e.g., 2 for IgG, 10 for IgM), and many antigens contain more than oneantigenic site. While binding avidity of an antibody depends on thebinding affinities of the individual antibody binding sites, bindingavidity is greater than the binding affinity as all the antibody-antigeninteractions must be broken simultaneously for the antibody todissociate completely. It is envisioned that an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond can selectivelybind to any and all epitopes for that antibody.

Thus, in an embodiment, an α-SNAP-25 antibody is an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond. In aspectsof this embodiment, an α-SNAP-25 antibody is an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminusglutamine or an α-SNAP-25 antibody that selectively binds to a SNAP-25epitope having a carboxyl-terminus lysine. In other aspects of thisembodiment, an α-SNAP-25 antibody is an α-SNAP-25 antibody thatselectively binds to a SNAP-25 epitope having a carboxyl-terminus P₁residue that corresponds to glutamine 197 of SEQ ID NO: 5 or anα-SNAP-25 antibody that selectively binds to a SNAP-25 epitope having acarboxyl-terminus P₁ residue that corresponds to lysine 204 of SEQ IDNO: 16. In still other aspects of this embodiment, an α-SNAP-25 antibodyis an α-SNAP-25 antibody that selectively binds to a SNAP-25 epitopehaving a carboxyl-terminal amino acid sequence of SEQ ID NO: 32, SEQ IDNO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQID NO: 39, SEQ ID NO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43,SEQ ID NO: 44, SEQ ID NO: 147 or SEQ ID NO: 148.

Aspects of the present disclosure comprise, in part, an immuno-basedmethod of detecting BoNT/A activity. The immuno-based methods disclosedin the present specification can be evaluated by several parametersincluding, e.g., accuracy, precision, limit of detection (LOD), limitsof quantitation (LOQ), linear range, specificity, selectivity,linearity, ruggedness, and system suitability. The accuracy of a methodis the measure of exactness of an analytical method, or the closeness ofagreement between the measured value and the value that is accepted as aconventional true value or an accepted reference value. The precision ofa method is the degree of agreement among individual test results, whenthe procedure is applied repeatedly to multiple samplings of ahomogeneous sample. As such, precision evaluates 1) within assayvariability; 2) within-day variability (repeatability); and 3)between-day variability (intermediate precision); and 4) between-labvariability (reproducibility). Coefficient of variation (CV %) is aquantitative measure of precision expressed relative to the observed ortheoretical mean value.

An immuno-based method disclosed in the present specification must beable to detect, over background, the presence of an α-SNAP-25antibody-antigen complex comprising a SNAP-25 having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond. The limitof detection (LOD) of a method refers to the concentration of analytewhich gives rise to a signal that is significantly different from thenegative control or blank and represents the lowest concentration ofanalyte that can be distinguished from background.

Thus, in an embodiment, the immuno-based method disclosed in the presentspecification can detect the LOD of BoNT/A at an amount that issignificantly different from a negative control or blank. In aspect ofthis embodiment, the immuno-based method disclosed in the presentspecification has an LOD of, e.g., 10 ng or less, 9 ng or less, 8 ng orless, 7 ng or less, 6 ng or less, 5 ng or less, 4 ng or less, 3 ng orless, 2 ng or less, 1 ng or less of a BoNT/A. In still other aspects ofthis embodiment, the immuno-based method disclosed in the presentspecification has an LOD of, e.g., 900 pg or less, 800 pg or less, 700pg or less, 600 pg or less, 500 pg or less, 400 pg or less, 300 pg orless, 200 pg or less, 100 pg or less of a BoNT/A. In further aspects ofthis embodiment, the immuno-based method disclosed in the presentspecification has an LOD of, e.g., 90 pg or less, 80 pg or less, 70 pgor less, 60 pg or less, 50 pg or less, 40 pg or less, 30 pg or less, 20pg or less, 10 pg or less of a BoNT/A. In other aspects of thisembodiment, the immuno-based method disclosed in the presentspecification has an LOD of, e.g., 9 pg or less, 8 pg or less, 7 pg orless, 6 pg or less, 5 pg or less, 4 pg or less, 3 pg or less, 2 pg orless, 1 pg or less of a BoNT/A. In yet other aspects of this embodiment,the immuno-based method disclosed in the present specification has anLOD of, e.g., 0.9 pg or less, 0.8 pg or less, 0.7 pg or less, 0.6 pg orless, 0.5 pg or less, 0.4 pg or less, 0.3 pg or less, 0.2 pg or less,0.1 pg or less of a BoNT/A.

In another aspect of this embodiment, the immuno-based method disclosedin the present specification has an LOD of, e.g., 10 nM or less or less,9 nM or less, 8 nM or less, 7 nM or less, 6 nM or less, 5 nM or less, 4nM or less, 3 nM or less, 2 nM or less, or 1 nM or less of a BoNT/A. Inother aspects of this embodiment, the immuno-based method disclosed inthe present specification has an LOD of, e.g., 900 pM or less, 800 pM orless, 700 pM or less, 600 pM or less, 500 pM or less, 400 pM or less,300 pM or less, 200 pM or less, or 100 pM or less of a BoNT/A. In otheraspects of this embodiment, the immuno-based method disclosed in thepresent specification has an LOD of, e.g., 100 pM or less, 90 pM orless, 80 pM or less, 70 pM or less, 60 pM or less, 50 pM or less, 40 pMor less, 30 pM or less, 20 pM or less, or 10 pM or less of a BoNT/A. Inyet other aspects of this embodiment, the immuno-based method disclosedin the present specification has an LOD of, e.g., 10 pM or less of aBoNT/A, 9 pM or less, 8 pM or less, 7 pM or less, 6 pM or less, 5 pM orless, 4 pM or less, 3 pM or less, 2 pM or less, or 1 pM or less of aBoNT/A. In still other aspects of this embodiment, the immuno-basedmethod disclosed in the present specification has an LOD of, e.g., 1000fM or less, 900 fM or less, 800 fM or less, 700 fM or less, 600 fM orless, 500 fM or less, 400 fM or less, 300 fM or less, 200 fM or less, or100 fM or less of a BoNT/A. In still other aspects of this embodiment,the immuno-based method disclosed in the present specification has anLOD of, e.g., 100 fM or less, 90 fM or less, 80 fM or less, 70 fM orless, 60 fM or less, 50 fM or less, 40 fM or less, 30 fM or less, 20 fMor less, or 10 fM or less of a BoNT/A. In still other aspects of thisembodiment, the immuno-based method disclosed in the presentspecification has an LOD of, e.g., 10 fM or less, 9 fM or less, 8 fM orless, 7 fM or less, 6 fM or less, 5 fM or less, 4 fM or less, 3 fM orless, 2 fM or less, or 1 fM or less of a botulinum neurotoxin A.

The limits of quantitation (LOQ) are the lowest and the highestconcentrations of analyte in a sample or specimen that can be measuredwith an acceptable level of accuracy and precision. The lower limit ofquantitation refers to the lowest dose that a detection method canmeasure consistently from the background. The upper limit ofquantitation is the highest dose that a detection method can measureconsistently before saturation of the signal occurs. The linear range ofthe method is the area between the lower and the upper limits ofquantitation. The linear range is calculated by subtracting lower limitof quantitation from the upper limit of quantitation. As used herein,the term “signal to noise ratio for the lower asymptote” refers to thesignal detected in the method at the lower limit of detection divided bythe background signal. As used herein, the term “signal to noise ratiofor the upper asymptote” refers to the signal detected in the method atthe upper limit of detection divided by the background signal.

Thus, in an embodiment, the immuno-based method disclosed in the presentspecification can detect the LOQ of BoNT/A at an amount that issignificantly different from a negative control or blank. In aspect ofthis embodiment, the immuno-based method disclosed in the presentspecification has an LOQ of, e.g., 10 ng or less, 9 ng or less, 8 ng orless, 7 ng or less, 6 ng or less, 5 ng or less, 4 ng or less, 3 ng orless, 2 ng or less, 1 ng or less of a BoNT/A. In still other aspects ofthis embodiment, the immuno-based method disclosed in the presentspecification has an LOQ of, e.g., 900 pg or less, 800 pg or less, 700pg or less, 600 pg or less, 500 pg or less, 400 pg or less, 300 pg orless, 200 pg or less, 100 pg or less of a BoNT/A. In further aspects ofthis embodiment, the immuno-based method disclosed in the presentspecification has an LOQ of, e.g., 90 pg or less, 80 pg or less, 70 pgor less, 60 pg or less, 50 pg or less, 40 pg or less, 30 pg or less, 20pg or less, 10 pg or less of a BoNT/A. In other aspects of thisembodiment, the immuno-based method disclosed in the presentspecification has an LOQ of, e.g., 9 pg or less, 8 pg or less, 7 pg orless, 6 pg or less, 5 pg or less, 4 pg or less, 3 pg or less, 2 pg orless, 1 pg or less of a BoNT/A. In yet other aspects of this embodiment,the immuno-based method disclosed in the present specification has anLOQ of, e.g., 0.9 pg or less, 0.8 pg or less, 0.7 pg or less, 0.6 pg orless, 0.5 pg or less, 0.4 pg or less, 0.3 pg or less, 0.2 pg or less,0.1 pg or less of a BoNT/A.

In another aspect of this embodiment, the immuno-based method disclosedin the present specification has an LOQ of, e.g., 10 nM or less, 9 nM orless, 8 nM or less, 7 nM or less, 6 nM or less, 5 nM or less, 4 nM orless, 3 nM or less, 2 nM or less, or 1 nM or less of a BoNT/A. In otheraspects of this embodiment, the immuno-based method disclosed in thepresent specification has an LOQ of, e.g., 900 pM or less, 800 pM orless, 700 pM or less, 600 pM or less, 500 pM or less, 400 pM or less,300 pM or less, 200 pM or less, or 100 pM or less of a BoNT/A. In otheraspects of this embodiment, the immuno-based method disclosed in thepresent specification has an LOQ of, e.g., 100 pM or less, 90 pM orless, 80 pM or less, 70 pM or less, 60 pM or less, 50 pM or less, 40 pMor less, 30 pM or less, 20 pM or less, or 10 pM or less of a BoNT/A. Inyet other aspects of this embodiment, the immuno-based method disclosedin the present specification has an LOQ of, e.g., 10 pM or less of aBoNT/A, 9 pM or less, 8 pM or less, 7 pM or less, 6 pM or less, 5 pM orless, 4 pM or less, 3 pM or less, 2 pM or less, or 1 pM or less of aBoNT/A. In still other aspects of this embodiment, the immuno-basedmethod disclosed in the present specification has an LOQ of, e.g., 1000fM or less, 900 fM or less, 800 fM or less, 700 fM or less, 600 fM orless, 500 fM or less, 400 fM or less, 300 fM or less, 200 fM or less, or100 fM or less of a BoNT/A. In still other aspects of this embodiment,the immuno-based method disclosed in the present specification has anLOQ of, e.g., 100 fM or less, 90 fM or less, 80 fM or less, 70 fM orless, 60 fM or less, 50 fM or less, 40 fM or less, 30 fM or less, 20 fMor less, or 10 fM or less of a BoNT/A. In still other aspects of thisembodiment, the immuno-based method disclosed in the presentspecification has an LOQ of, e.g., 10 fM or less, 9 fM or less, 8 fM orless, 7 fM or less, 6 fM or less, 5 fM or less, 4 fM or less, 3 fM orless, 2 fM or less, or 1 fM or less of a BoNT/A.

An immuno-based assay useful to practice aspect of the disclosed methodsmust have a precision of no more than 50%. In aspects of thisembodiment, an immuno-based assay has a precision of no more than 50%,no more than 40%, no more than 30%, or no more than 20%. In otheraspects of this embodiment, an immuno-based assay has a precision of normore than 15%, no more than 10%, or no more than 5%. In other aspects ofthis embodiment, an immuno-based assay has a precision of nor more than4%, no more than 3%, no more than 2%, or no more than 1%.

An immuno-based assay useful to practice aspect of the disclosed methodsmust have an accuracy of at least 50%. In aspects of this embodiment, animmuno-based assay has an accuracy of at least 50%, at least 60%, atleast 70%, or at least 80%. In other aspects of this embodiment, animmuno-based assay has an accuracy of at least 85%, at least 90%, or atleast 95%. In other aspects of this embodiment, an immuno-based assayhas an accuracy of at least 96%, at least 97%, at least 98%, or at least99%.

An immuno-based method disclosed in the present specification must havea signal to noise ratio for the lower asymptote that is statisticallysignificant and a signal to noise ratio for the upper asymptote that isstatistically significant. In aspects of this embodiment, animmuno-based method disclosed in the present specification has a signalto noise ratio for the lower asymptote of, e.g., at least 3:1, at least4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least9:1, at least 10:1, at least 15:1 or at least 20:1. In other aspects ofthis embodiment, an immuno-based method has a signal to noise ratio forthe upper asymptote of, e.g., at least 10:1, at least 15:1, at least20:1, at least 25:1, at least 30:1, at least 35:1, at least 40:1, atleast 45:1, at least 50:1, at least 60:1, at least 70:1, at least 80:1,at least 90:1, or at least 100:1, at least 150:1, at least 200:1, atleast 250:1, at least 300:1, at least 350:1, at least 400:1, at least450:1, at least 500:1, at least 550:1, or at least 600:1.

The specificity of a method defines the ability of the method to measurethe analyte of interest to the exclusion of other relevant components,such as, e.g., partially-active or inactive analyte. The selectivity ofa method describes the ability of an analytical method to differentiatevarious substances in a sample. The linearity of a method is its abilityto elicit results that are directly, or by a well defined mathematicaltransformation, proportional to the concentration of analyte in thesample. Thus in an embodiment, an immuno-based method disclosed in thepresent specification can distinguish a fully-active BoNT/A from apartially-active BoNT/A having, e.g., 70% or less, 60% or less, 50% orless, 40% or less, 30% or less, 20% or less, or 10% or less the activityof a fully-active BoNT/A.

The ruggedness of the method is the reproducibility of the test resultsobtained for identical samples under normal (but variable) testconditions. Robustness of a procedure is a measure of its capacity toremain unaffected by small but deliberate variations in the methodparameters and provides an indication of its reliability in normalusage. Thus, whereas ruggedness evaluates unavoidable changes,robustness evaluates deliberate changes. Typical parameters evaluated byruggedness and robustness include the effects of freeze/thaw, incubationtimes, incubation temperature, longevity of reagent, sample preparation,sample storage, cell passage number, lots of toxin, variability betweenpurifications, and variability between nicking reactions. Robustnessparameters for cell-based assays include the cell bank (beginning,middle and end of freeze), cell passage level, cell seeding density,cell stock density (how many days in culture), cell age in flask(waiting time to seeding), incubation time, different plates, excessiveamounts of serum, and source of reagents. The system suitability of themethod is the determination of assay performance, including theperformance of reagents and instruments, over time by analysis of areference standard. System suitability is stressed in FDA guidancereferring to the fact that equipment, electronics, assay performance,and samples to be analyzed, constitute an integrated system. Systemsuitability can be evaluated by testing for parallelism, which is whenplotting the log dose versus the response, serial dilutions of thereference and serial dilutions of the samples should give rise toparallel curves.

Aspects of the present disclosure comprise, in part, a cell from anestablished cell line. As used herein, the term “cell” refers to anyeukaryotic cell susceptible to BoNT/A intoxication by a BoNT/A or anyeukaryotic cell that can uptake a BoNT/A. The term cell encompassescells from a variety of organisms, such as, e.g., murine, rat, porcine,bovine, equine, primate and human cells; from a variety of cell typessuch as, e.g., neuronal and non-neuronal; and can be isolated from orpart of a heterogeneous cell population, tissue or organism. As usedherein, the term “established cell line” is synonymous with “immortalcell line,” or “transformed cell line” and refers to a cell culture ofcells selected for indefinite propagation from a cell population derivedfrom an organism, tissue, or organ source. By definition, an establishedcell line excludes a cell culture of primary cells. As used herein, theterm “primary cells” are cells harvested directly from fresh tissues ororgans and do not have the potential to propagate indefinitely. Anestablished cell line can comprise a heterogeneous population of cellsor a uniform population of cells. An established cell line derived froma single cell is referred to as a clonal cell line. An established cellline can be one whose cells endogenously express all component necessaryfor the cells to undergo the overall cellular mechanism whereby a BoNT/Aproteolytically cleaves a SNAP-25 substrate and encompasses the bindingof a BoNT/A to a BoNT/A receptor, the internalization of theneurotoxin/receptor complex, the translocation of the BoNT/A light chainfrom an intracellular vesicle into the cytoplasm and the proteolyticcleavage of a SNAP-25. Alternatively, an established cell line can beone whose cells have had introduced from an exogenous source at leastone component necessary for the cells to undergo the overall cellularmechanism whereby a BoNT/A proteolytically cleaves a SNAP-25 substrateand encompasses the binding of a BoNT/A to a BoNT/A receptor, theinternalization of the neurotoxin/receptor complex, the translocation ofthe BoNT/A light chain from an intracellular vesicle into the cytoplasmand the proteolytic cleavage of a SNAP-25. Also refereed to as agenetically-engineered cell line, cells from such an established cellline may, e.g., express an exogenous FGFR2, an exogenous FGFR3, anexogenous SV2, an exogenous SNAP-25, or any combination thereof.

Aspects of the present disclosure comprise, in part, a cell from anestablished cell line susceptible to BoNT/A intoxication. As usedherein, the terms “cell(s) susceptible to BoNT/A intoxication,” “cell(s)susceptible to BoNT/A intoxication by a BoNT/A,” or “cell(s) from anestablished cell line susceptible to BoNT/A intoxication by a BoNT/A”refer to cell(s) that can undergo the overall cellular mechanism wherebya BoNT/A proteolytically cleaves a SNAP-25 substrate and encompasses thebinding of a BoNT/A to a BoNT/A receptor, the internalization of theneurotoxin/receptor complex, the translocation of the BoNT/A light chainfrom an intracellular vesicle into the cytoplasm and the proteolyticcleavage of a SNAP-25. By definition, cell(s) susceptible to of BoNT/Aintoxication must express, or be engineered to express, at least oneBoNT/A receptor and at least one SNAP-25 substrate. As used herein, theterms “cell(s) that can uptake BoNT/A” or “cell(s) comprising anestablished cell line that can uptake BoNT/A” refer to cells that canundergo the overall cellular mechanism whereby a BoNT/A proteolyticallycleaves a SNAP-25 substrate and encompasses the binding of a BoNT/A to aBoNT/A receptor, the internalization of the neurotoxin/receptor complex,the translocation of the BoNT/A light chain from an intracellularvesicle into the cytoplasm and the proteolytic cleavage of a SNAP-25. Bydefinition, cell(s) that can uptake BoNT/A must express, or beengineered to express, at least one BoNT/A receptor and at least oneSNAP-25 substrate.

Thus in an embodiment, cells from an established cell line aresusceptible to BoNT/A intoxication. In aspects of this embodiment, cellsfrom an established cell line are susceptible to BoNT/A intoxication by,e.g., about 500 pM or less, about 400 pM or less, about 300 pM or less,about 200 pM or less, or about 100 pM or less of a BoNT/A. In otheraspects of this embodiment, cells from an established cell line aresusceptible to BoNT/A intoxication by, e.g., about 90 pM or less, about80 pM or less, about 70 pM or less, about 60 pM or less, about 50 pM orless, about 40 pM or less, about 30 pM or less, about 20 pM or less A,or about 10 pM or less of a BoNT/A. In still other aspects, cells froman established cell line are susceptible to BoNT/A intoxication by,e.g., about 9 pM or less, about 8 pM or less, about 7 pM or less, about6 pM or less, about 5 pM or less, about 4 pM or less, about 3 pM orless, about 2 pM or less, or about 1 pM or less of a BoNT/A. In yetother aspects, cells from an established cell line are susceptible toBoNT/A intoxication by, e.g., about 0.9 pM or less, about 0.8 pM orless, about 0.7 pM or less, about 0.6 pM or less, about 0.5 pM or less,about 0.4 pM or less, about 0.3 pM or less, about 0.2 pM, or about 0.1pM or less of a BoNT/A. As used herein, the term “about” when qualifyinga value of a stated item, number, percentage, or term refers to a rangeof plus or minus ten percent of the value of the stated item,percentage, parameter, or term.

In another embodiment, cells comprising an established cell line canuptake a BoNT/A. In aspects of this embodiment, cells comprising anestablished cell line can uptake, e.g., about 500 pM or less, about 400pM or less, about 300 pM or less, about 200 pM or less, or about 100 pMor less of a BoNT/A. In other aspects of this embodiment, cellscomprising an established cell line possess the ability to uptake about90 pM or less, about 80 pM or less, about 70 pM or less, about 60 pM orless, about 50 pM or less, about 40 pM or less, about 30 pM or less,about 20 pM or less, or about 10 pM or less of a BoNT/A. In still otheraspects, cells comprising an established cell line possess the abilityto uptake about 9 pM or less, about 8 pM or less, about 7 pM or less,about 6 pM or less, about 5 pM or less, about 4 pM or less, about 3 pMor less, about 2 pM or less, or about 1 pM or less of a BoNT/A. In yetother aspects, cells comprising an established cell line possess theability to uptake about 0.9 pM or less, about 0.8 pM or less, about 0.7pM or less, about 0.6 pM or less, about 0.5 pM or less, about 0.4 pM orless, about 0.3 pM or less, about 0.2 pM or less, or about 0.1 pM orless of a BoNT/A.

Aspects of the present disclosure comprise, in part, a BoNT/A. As usedherein, the term “BoNT/A” is synonymous with “botulinum neurotoxinserotype A” or “botulinum neurotoxin type A” and refers to both anaturally-occurring BoNT/A or a non-naturally occurring BoNT/As thereof,and includes BoNT/A complex comprising the about 150 kDa BoNT/Aneurotoxin and associated non-toxin associated proteins (NAPs), as wellas the about 150 kDa BoNT/A neurotoxin alone. Non-limiting examples ofBoNT/A complexes include, e.g., the 900-kDa BoNT/A complex, the 500-kDaBoNT/A complex, the 300-kDa BoNT/A complex. Non-limiting examples of theabout 150 kDa BoNT/A neurotoxin include, e.g., SEQ ID NO: 1, SEQ ID NO:2, SEQ ID NO: 3, SEQ ID NO: 4.

As used herein, the term “naturally occurring BoNT/A” refers to anyBoNT/A produced by a naturally-occurring process, including, withoutlimitation, BoNT/A isoforms produced from a post-translationalmodification, an alternatively-spliced transcript, or a spontaneousmutation, and BoNT/A subtypes, such as, e.g., a BoNT/A1 subtype, BoNT/A2subtype, BoNT/A3 subtype, BoNT/A4 subtype, and BoNT/A5 subtype. Anaturally occurring BoNT/A includes, without limitation, SEQ ID NO: 1,SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, or one that substitutes,deletes or adds, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 ormore, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 ormore, 30 or more, 40 or more, 50 or more, or 100 amino acids from SEQ IDNO: 1, SEQ ID NO: 2, SEQ ID NO: 3, or SEQ ID NO: 4. Commerciallyavailable pharmaceutical compositions of a naturally-occurring BoNT/Aincludes, without limitation, BOTOX® (Allergan, Inc., Irvine, Calif.),DYSPORT®/RELOXIN®, (Ipsen Ltd., Slough, England), PURTOX® (Mentor Corp.,Santa Barbara, Calif.), XEOMIN® (Merz Pharmaceuticals, GmbH., Frankfurt,Germany), NEURONOX® (Medy-Tox, Inc., Ochang-myeon, South Korea), BTX-A.

As used herein, the term “non-naturally occurring BoNT/A” refers to anyBoNT/A whose structure was modified with the aid of human manipulation,including, without limitation, a BoNT/A with an altered amino acidsequence produced by genetic engineering using random mutagenesis orrational design and a BoNT/A produced by in vitro chemical synthesis.Non-limiting examples of non-naturally occurring BoNT/As are describedin, e.g., Steward, L. E. et al., Post-translational Modifications andClostridial Neurotoxins, U.S. Pat. No. 7,223,577; Dolly, J. O. et al.,Activatable Clostridial Toxins, U.S. Pat. No. 7,419,676; Steward, L. E.et al., Clostridial Neurotoxin Compositions and Modified ClostridialNeurotoxins, US 2004/0220386; Steward, L. E. et al., ModifiedClostridial Toxins With Enhanced Targeting Capabilities For EndogenousClostridial Toxin Receptor Systems, U.S. Patent Publication No.2008/0096248; Steward, L. E. et al., Modified Clostridial Toxins WithAltered Targeting Capabilities For Clostridial Toxin Target Cells, U.S.Patent Publication No. 2008/0161543; Steward, L. E. et al., ModifiedClostridial Toxins With Enhanced Translocation Capabilities and AlteredTargeting Activity For Clostridial Toxin Target Cells, U.S. PatentPublication No. 2008/0241881, each of which is hereby incorporated byreference in its entirety.

Thus in an embodiment, the BoNT/A activity being detected is from anaturally occurring BoNT/A. In aspects of this embodiment, the BoNT/Aactivity being detected is from a BoNT/A isoform or a BoNT/A subtype. Inaspects of this embodiment, the BoNT/A activity being detected is fromthe BoNT/A of SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, or SEQ ID NO: 4.In other aspects of this embodiment, the BoNT/A activity being detectedis from a BoNT/A having, e.g., at least 70%, at least 75%, at least 80%,at least 85%, at least 90%, or at least 95% amino acid identity with SEQID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, or SEQ ID NO: 4. In other aspectsof this embodiment, the BoNT/A activity being detected is from BOTOX®,DYSPORT®/RELOXIN®, PURTOX®, XEOMIN®, NEURONOX®, or BTX-A.

In another embodiment, the BoNT/A activity being detected is from anon-naturally occurring BoNT/A. In other aspects of this embodiment, theBoNT/A activity being detected is from a non-naturally occurring BoNT/Avariant having, e.g., at least 70%, at least 75%, at least 80%, at least85%, at least 90%, or at least 95% amino acid identity with SEQ ID NO:1, SEQ ID NO: 2, SEQ ID NO: 3, or SEQ ID NO: 4. In other aspects of thisembodiment, the BoNT/A activity being detected is from a non-naturallyoccurring BoNT/A variant having, e.g., 1 or more, 2 or more, 3 or more,4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 ormore, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or morenon-contiguous amino acid substitutions, deletions, or additionsrelative to SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, or SEQ ID NO: 4.In yet other aspects of this embodiment, the BoNT/A activity beingdetected is from a non-naturally occurring BoNT/A variant having, e.g.,1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 ormore, 8 or more, 9 or more, 10 or more, 20 or more, 30 or more, 40 ormore, 50 or more, or 100 or more contiguous amino acid substitutions,deletions, or additions relative to SEQ ID NO: 1, SEQ ID NO: 2, SEQ IDNO: 3, or SEQ ID NO: 4.

Aspects of the present disclosure comprise, in part, a SNAP-25. As usedherein, the term “SNAP-25” refers to a naturally-occurring SNAP-25 or anon-naturally occurring SNAP-25 which is preferentially cleaved by aBoNT/A. As used herein, the term “preferentially cleaved” refers to thatthe cleavage rate of BoNT/A substrate by a BoNT/A is at least one orderof magnitude higher than the cleavage rate of any other substrate byBoNT/A. In aspects of this embodiment, the cleavage rate of BoNT/Asubstrate by a BoNT/A is at least two orders of magnitude higher, atleast three orders of magnitude higher, at least four orders ofmagnitude higher, or at least five orders of magnitude higher then thatthe cleavage rate of any other substrate by BoNT/A.

As used herein, the term “naturally occurring SNAP-25” refers to anySNAP-25 produced by a naturally-occurring process, including, withoutlimitation, SNAP-25 isoforms produced from a post-translationalmodification, an alternatively-spliced transcript, or a spontaneousmutation, and SNAP-25 subtypes. A naturally occurring SNAP-25 includes,without limitation, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO:8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO:13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ IDNO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQID NO: 23, or SEQ ID NO: 24, or one that substitutes, deletes or adds,e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more,7 or more, 8 or more, 9 or more, 10 or more, 20 or more, 30 or more, 40or more, 50 or more, or 100 or more amino acids from SEQ ID NO: 5, SEQID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15,SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO:20, SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, or SEQ ID NO: 24.

As used herein, the term “non-naturally occurring SNAP-25” refers to anySNAP-25 whose structure was modified with the aid of human manipulation,including, without limitation, a SNAP-25 produced by genetic engineeringusing random mutagenesis or rational design and a SNAP-25 produced by invitro chemical synthesis. Non-limiting examples of non-naturallyoccurring SNAP-25s are described in, e.g., Steward, L. E. et al., FRETProtease Assays for Clostridial Toxins, U.S. Pat. No. 7,332,567;Fernandez-Salas et al., Lipohilic Dye-based FRET Assays for ClostridialToxin Activity, U.S. Patent Publication 2008/0160561, each of which ishereby incorporated by reference in its entirety. A non-naturallyoccurring SNAP-25 may substitute, delete or add, e.g., 1 or more, 2 ormore, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more,9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more,or 100 or more amino acids from SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO:7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO:12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ IDNO: 17, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQID NO: 22, SEQ ID NO: 23, or SEQ ID NO: 24.

Thus in an embodiment, a SNAP-25 is a naturally occurring SNAP-25. Inaspects of this embodiment, the SNAP-25 is a SNAP-25 isoform or aSNAP-25 subtype. In aspects of this embodiment, the naturally occurringSNAP-25 is the naturally occurring SNAP-25 of SEQ ID NO: 5, SEQ ID NO:6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO:11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ IDNO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, or SEQ ID NO: 24. In otheraspects of this embodiment, the SNAP-25 is a naturally occurring SNAP-25having, e.g., at least 70% amino acid identity, at least 75%, at least80%, at least 85%, at least 90%, or at least 95% amino acid identitywith SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO:9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ IDNO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23,or SEQ ID NO: 24.

In another embodiment, a SNAP-25 is a non-naturally occurring SNAP-25.In other aspects of this embodiment, the SNAP-25 is a non-naturallyoccurring SNAP-25 having, e.g., at least 70%, at least 75%, at least80%, at least 85%, at least 90%, or at least 95% amino acid identitywith SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, or SEQ ID NO: 4. In otheraspects of this embodiment, the SNAP-25 is a non-naturally occurringSNAP-25 having, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 ormore, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 ormore, 30 or more, 40 or more, 50 or more, or 100 or more non-contiguousamino acid substitutions, deletions, or additions relative to SEQ ID NO:5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO:10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ IDNO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, SEQID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, or SEQ ID NO:24. In yet other aspects of this embodiment, the SNAP-25 is anon-naturally occurring SNAP-25 having, e.g., 1 or more, 2 or more, 3 ormore, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more,10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100 ormore contiguous amino acid substitutions, deletions, or additionsrelative to SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13,SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO:18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQ IDNO: 23, or SEQ ID NO: 24.

A SNAP-25 can be an endogenous SNAP-25 or an exogenous SNAP-25. As usedherein, the term “endogenous SNAP-25” refers to a SNAP-25 naturallypresent in the cell because it is naturally encoded within the cell'sgenome, such that the cell inherently expresses the SNAP-25 without theneed an external source of SNAP-25 or an external source of geneticmaterial encoding a SNAP-25. The expression of an endogenous SNAP-25 maybe with or without environmental stimulation such as, e.g., celldifferentiation. By definition, an endogenous SNAP-25 can only be anaturally-occurring SNAP-25 or variants thereof. For example, thefollowing established cell lines express an endogenous SNAP-25:BE(2)-M17, Kelly, LA1-55n, N1E-115, N4TG3, N18, Neuro-2a, NG108-15,PC12, SH-SYSY, SiMa, and SK-N-BE(2)-C.

As used herein, the term “exogenous SNAP-25” refers to a SNAP-25expressed in a cell through the introduction of an external source ofSNAP-25 or an external source of genetic material encoding a SNAP-25 byhuman manipulation. The expression of an exogenous SNAP-25 may be withor without environmental stimulation such as, e.g., celldifferentiation. As a non-limiting example, cells from an establishedcell line can express an exogenous SNAP-25 by transient or stablytransfection of a SNAP-25. As another non-limiting example, cells froman established cell line can express an exogenous SNAP-25 by proteintransfection of a SNAP-25. An exogenous SNAP-25 can be anaturally-occurring SNAP-25 or variants thereof, or a non-naturallyoccurring SNAP-25 or variants thereof.

Thus in an embodiment, cells from an established cell line express anendogenous SNAP-25. In aspects of this embodiment, the endogenousSNAP-25 expressed by cells from an established cell line is anaturally-occurring SNAP-25. In other aspects of this embodiment, theendogenous SNAP-25 expressed by cells from an established cell line isSEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9,SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO:14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ IDNO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, orSEQ ID NO: 24. In yet aspects of this embodiment, the endogenous SNAP-25expressed by cells from an established cell line is a naturallyoccurring SNAP-25, such as, e.g., a SNAP-25 isoform or a SNAP-25subtype. In other aspects of this embodiment, the endogenous SNAP-25expressed by cells from an established cell line is a naturallyoccurring SNAP-25 having, e.g., at least 70% amino acid identity, atleast 75%, at least 80%, at least 85%, at least 90%, or at least 95%amino acid identity with SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17,SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO:22, SEQ ID NO: 23, or SEQ ID NO: 24.

In another embodiment, cells from an established cell line aretransiently or stably engineered to express an exogenous SNAP-25. In anaspect of this embodiment, cells from an established cell line aretransiently or stably engineered to express a naturally-occurringSNAP-25. In other aspects of this embodiment, cells from an establishedcell line are transiently or stably engineered to express thenaturally-occurring SNAP-25 of SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7,SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12,SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO:17, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ IDNO: 22, SEQ ID NO: 23, or SEQ ID NO: 24. In yet other aspects of thisembodiment, cells from an established cell line are transiently orstably engineered to express a naturally occurring SNAP-25, such as,e.g., a SNAP-25 isoform or a SNAP-25 subtype. In still other aspects ofthis embodiment, cells from an established cell line are transiently orstably engineered to express a naturally occurring SNAP-25 having, e.g.,at least 70% amino acid identity, at least 75%, at least 80%, at least85%, at least 90%, or at least 95% amino acid identity with SEQ ID NO:5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO:10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ IDNO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, SEQID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, or SEQ ID NO:24.

In another aspect of the embodiment, cells from an established cell lineare transiently or stably engineered to express a non-naturallyoccurring SNAP-25. In other aspects of this embodiment, cells from anestablished cell line are transiently or stably engineered to express anon-naturally occurring SNAP-25 having, e.g., at least 70%, at least75%, at least 80%, at least 85%, at least 90%, or at least 95% aminoacid identity with SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO:8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO:13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ IDNO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, SEQID NO: 23, or SEQ ID NO: 24. In other aspects of this embodiment, cellsfrom an established cell line are transiently or stably engineered toexpress a non-naturally occurring SNAP-25 having, e.g., 1 or more, 2 ormore, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more,9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more,or 100 or more non-contiguous amino acid substitutions, deletions, oradditions relative to SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ IDNO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ IDNO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22,SEQ ID NO: 23, or SEQ ID NO: 24. In yet other aspects of thisembodiment, cells from an established cell line are transiently orstably engineered to express a non-naturally occurring SNAP-25 having,e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more,7 or more, 8 or more, 9 or more, 10 or more, 20 or more, 30 or more, 40or more, 50 or more, or 100 or more contiguous amino acid substitutions,deletions, or additions relative to SEQ ID NO: 5, SEQ ID NO: 6, SEQ IDNO: 7, SEQ ID NO: 8, SEQ ID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ IDNO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 21,SEQ ID NO: 22, SEQ ID NO: 23, or SEQ ID NO: 24.

Assays that detect the cleavage of a BoNT/A substrate after exposure toa BoNT/A can be used to assess whether a cell is expressing anendogenous or exogenous SNAP-25. In these assays, generation of aSNAP-25 cleavage-product would be detected in cells expressing a SNAP-25after BoNT/A treatment. Non-limiting examples of specific Western blotanalysis, as well as well-characterized reagents, conditions andprotocols are readily available from commercial vendors that include,without limitation, Amersham Biosciences, Piscataway, N.J.; Bio-RadLaboratories, Hercules, Calif.; Pierce Biotechnology, Inc., Rockford,Ill.; Promega Corporation, Madison, Wis., and Stratagene, Inc., LaJolla, Calif. It is understood that these and similar assays for SNAP-25cleavage can be useful in identifying cells expressing an endogenous oran exogenous SNAP-25.

As non-limiting examples, Western blot analysis using an antibody thatrecognizes BoNT/A SNAP-25-cleaved product or both the cleaved anduncleaved forms of SNAP-25 can be used to assay for uptake of BoNT/A.Examples of α-SNAP-25 antibodies useful for these assays include,without limitation, α-SNAP-25 mouse monoclonal antibody SMI-81(Sternberger Monoclonals Inc., Lutherville, Md.), mouse α-SNAP-25monoclonal antibody CI 71.1 (Synaptic Systems, Goettingen, Germany),α-SNAP-25 mouse monoclonal antibody CI 71.2 (Synaptic Systems,Goettingen, Germany), α-SNAP-25 mouse monoclonal antibody SP12 (Abcam,Cambridge, Mass.), α-SNAP-25 rabbit polyclonal antiserum (SynapticSystems, Goettingen, Germany), α-SNAP-25 rabbit polyclonal antiserum(Abcam, Cambridge, Mass.), and α-SNAP-25 rabbit polyclonal antiserumS9684 (Sigma, St Louis, Mo.).

Aspects of the present disclosure comprise, in part, a BoNT/A receptor.As used herein, the term “BoNT/A receptor” refers to either anaturally-occurring BoNT/A receptor or a non-naturally occurring BoNT/Areceptor which preferentially interacts with BoNT/A in a manner thatelicits a BoNT/A intoxication response. As used herein, the term“preferentially interacts” refers to that the equilibrium dissociationconstant (KD) of BoNT/A for a BoNT/A receptor is at least one order ofmagnitude less than that of BoNT/A for any other receptor at the cellsurface. The equilibrium dissociation constant, a specific type ofequilibrium constant that measures the propensity of an BoNT/A-BoNT/Areceptor complex to separate (dissociate) reversibly into its componentmolecules, namely the BoNT/A and the BoNT/A receptor, is defined asKD=Ka/Kd at equilibrium. The association constant (Ka) is defined asKa=[C]/[L][R] and the disassociation constant (Kd) is defined asKd=[L][R]/[C], where [L] equals the molar concentration of BoNT/A, [R]is the molar concentration of a BoNT/A receptor, and [C] is the molarconcentration of the BoNT/A-BoNT/A receptor complex, and where allconcentrations are of such components when the system is at equilibrium.The smaller the dissociation constant, the more tightly bound the BoNT/Ais to its receptor, or the higher the binding affinity between BoNT/Aand BoNT/A receptor. In aspects of this embodiment, the disassociationconstant of BoNT/A for a BoNT/A receptor is at least two orders ofmagnitude less, at least three orders of magnitude less, at least fourorders of magnitude less, or at least five orders of magnitude less thanthat of BoNT/A for any other receptor. In other aspects of thisembodiment, the binding affinity of a BoNT/A that preferentiallyinteracts with a BoNT/A receptor can have an equilibrium disassociationconstant (KD) of, e.g., of 500 nM or less, 400 nM or less, 300 nM orless, 200 nM, or less 100 nM or less. In other aspects of thisembodiment, the binding affinity of a BoNT/A that preferentiallyinteracts with a BoNT/A receptor can have an equilibrium disassociationconstant (KD) of, e.g., of 90 nM or less, 80 nM or less, 70 nM or less,60 nM, 50 nM or less, 40 nM or less, 30 nM or less, 20 nM, or less 10 nMor less. As used herein, the term “elicits a BoNT/A intoxicationresponse” refers to the ability of a BoNT/A receptor to interact with aBoNT/A to form a neurotoxin/receptor complex and the subsequentinternalization of that complex into the cell cytoplasm.

As used herein, the term “naturally occurring BoNT/A receptor” refers toany BoNT/A receptor produced by a naturally-occurring process,including, without limitation, BoNT/A receptor isoforms produced from apost-translational modification, an alternatively-spliced transcript, ora spontaneous mutation, and BoNT/A receptor subtypes. A naturallyoccurring BoNT/A receptor includes, without limitation, a fibroblastgrowth factor receptor 2 (FGFR2), a fibroblast growth factor receptor 3(FGFR3), a synaptic vesicle glycoprotein 2 (SV2), and a complexganglioside like GT1b, such as those described in Ester Fernandez-Salas,et al., Botulinum Toxin Screening Assays, U.S. Patent Publication2008/0003240; Ester Fernandez-Salas, et al., Botulinum Toxin ScreeningAssays, U.S. Patent Publication 2008/0182799; Min Dong et al., SV2 isthe Protein Receptor for Botulinum Neurotoxin A, Science (2006); S.Mahrhold et al, The Synaptic Vesicle Protein 2C Mediates the Uptake ofBotulinum Neurotoxin A into Phrenic Nerves, 580(8) FEBS Lett. 2011-2014(2006), each of which is hereby incorporated by reference in itsentirety. A naturally occurring FGFR2 includes, without limitation, SEQID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63,SEQ ID NO: 64, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO:68, SEQ ID NO: 69, and SEQ ID NO: 70, or one that substitutes, deletesor adds, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 or more, 30 ormore, 40 or more, 50 or more, or 100 or more amino acids from SEQ ID NO:59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63, SEQ IDNO: 64, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 68, SEQID NO: 69, and SEQ ID NO: 70. A naturally occurring FGFR3 includes,without limitation, SEQ ID NO: 25, SEQ ID NO: 26, and SEQ ID NO: 27, orone that substitutes, deletes or adds, e.g., 1 or more, 2 or more, 3 ormore, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more,10 or more, 20 or more, 30 or more, 40 or more, 50 or more, or 100 ormore amino acids from SEQ ID NO: 25, SEQ ID NO: 26, and SEQ ID NO: 27. Anaturally occurring SV2 includes, without limitation, SEQ ID NO: 28, SEQID NO: 29, SEQ ID NO: 30, and SEQ ID NO: 31, or one that substitutes,deletes or adds, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 ormore, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 ormore, 30 or more, 40 or more, 50 or more, or 100 or more amino acidsfrom SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, and SEQ ID NO: 31.

As used herein, the term “non-naturally occurring BoNT/A receptorvariant” refers to any BoNT/A receptor produced with the aid of humanmanipulation or design, including, without limitation, a BoNT/A receptorproduced by genetic engineering using random mutagenesis or rationaldesign and a BoNT/A receptor produced by chemical synthesis.Non-limiting examples of non-naturally occurring BoNT/A variantsinclude, e.g., conservative BoNT/A receptor variants, non-conservativeBoNT/A receptor variants, BoNT/A receptor chimeric variants and activeBoNT/A receptor fragments.

As used herein, the term “non-naturally occurring BoNT/A receptor”refers to any BoNT/A receptor whose structure was modified with the aidof human manipulation, including, without limitation, a BoNT/A receptorproduced by genetic engineering using random mutagenesis or rationaldesign and a BoNT/A receptor produced by in vitro chemical synthesis.Non-limiting examples of non-naturally occurring BoNT/A receptors aredescribed in, e.g., Ester Fernandez-Salas, et al., Botulinum ToxinScreening Assays, U.S. Patent Publication 2008/0003240; EsterFernandez-Salas, et al., Botulinum Toxin Screening Assays, U.S. PatentPublication 2008/0182799, each of which is hereby incorporated byreference in its entirety. A non-naturally occurring BoNT/A receptor maysubstitute, delete or add, e.g., 1 or more, 2 or more, 3 or more, 4 ormore, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more,20 or more, 30 or more, 40 or more, 50 or more, or 100 or more aminoacids from SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28,SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO: 59, SEQ ID NO:60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63, SEQ ID NO: 64, SEQ IDNO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 68, SEQ ID NO: 69, orSEQ ID NO: 70.

Thus in an embodiment, a BoNT/A receptor is a naturally occurring BoNT/Areceptor such as, e.g., FGFR2, FGFR3 or SV2. In aspects of thisembodiment, the BoNT/A receptor is a BoNT/A receptor isoform or a BoNT/Areceptor subtype. In aspects of this embodiment, the naturally occurringBoNT/A receptor is the naturally occurring BoNT/A receptor of SEQ ID NO:25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ IDNO: 30, SEQ ID NO: 31, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQID NO: 62, SEQ ID NO: 63, SEQ ID NO: 64, SEQ ID NO: 65, SEQ ID NO: 66,SEQ ID NO: 67, SEQ ID NO: 68, SEQ ID NO: 69, or SEQ ID NO: 70. In otheraspects of this embodiment, the BoNT/A receptor is a naturally occurringBoNT/A receptor having, e.g., at least 70% amino acid identity, at least75%, at least 80%, at least 85%, at least 90%, or at least 95% aminoacid identity with SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ IDNO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO: 59, SEQID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63, SEQ ID NO: 64,SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 68, SEQ ID NO:69, or SEQ ID NO: 70.

In another embodiment, a BoNT/A receptor is a non-naturally occurringBoNT/A receptor, such as, e.g., a genetically-engineered FGFR2, agenetically-engineered FGFR3, or a genetically-engineered SV2. In otheraspects of this embodiment, the BoNT/A receptor is a non-naturallyoccurring BoNT/A receptor having, e.g., at least 70%, at least 75%, atleast 80%, at least 85%, at least 90%, or at least 95% amino acididentity with SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO:28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO: 59, SEQ IDNO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63, SEQ ID NO: 64, SEQID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 68, SEQ ID NO: 69,or SEQ ID NO: 70. In other aspects of this embodiment, the BoNT/Areceptor is a non-naturally occurring BoNT/A receptor having, e.g., 1 ormore, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more,8 or more, 9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50or more, or 100 or more non-contiguous amino acid substitutions,deletions, or additions relative to SEQ ID NO: 25, SEQ ID NO: 26, SEQ IDNO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63,SEQ ID NO: 64, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO:68, SEQ ID NO: 69, or SEQ ID NO: 70. In yet other aspects of thisembodiment, the BoNT/A receptor is a non-naturally occurring BoNT/Areceptor having, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 ormore, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 ormore, 30 or more, 40 or more, 50 or more, or 100 or more contiguousamino acid substitutions, deletions, or additions relative to SEQ ID NO:25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ IDNO: 30, SEQ ID NO: 31, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQID NO: 62, SEQ ID NO: 63, SEQ ID NO: 64, SEQ ID NO: 65, SEQ ID NO: 66,SEQ ID NO: 67, SEQ ID NO: 68, SEQ ID NO: 69, or SEQ ID NO: 70.

A BoNT/A receptor can be an endogenous BoNT/A receptor or an exogenousBoNT/A receptor. As used herein, the term “endogenous BoNT/A receptor”refers to a BoNT/A receptor naturally present in the cell because it isnaturally encoded within the cell's genome, such that the cellinherently expresses the BoNT/A receptor without the need for anexternal source of BoNT/A receptor or an external source of geneticmaterial encoding a BoNT/A receptor. Expression of an endogenous BoNT/Areceptor may be with or without environmental stimulation such as e.g.,cell differentiation or promoter activation. For example, the followingestablished cell lines express at least one endogenous BoNT/A receptor:BE(2)-M17, Kelly, LA1-55n, N1E-115, N4TG3, N18, Neuro-2a, NG108-15,PC12, SH-SYSY, SiMa, and SK-N-BE(2)-C. An endogenous BoNT/A receptor canonly be a naturally-occurring BoNT/A receptor or naturally-occurringvariants thereof.

As used herein, the term “exogenous BoNT/A receptor” refers to a BoNT/Areceptor expressed in a cell through the introduction of an externalsource of BoNT/A receptor or an external source of genetic materialencoding a BoNT/A receptor by human manipulation. The expression of anexogenous BoNT/A receptor may be with or without environmentalstimulation such as, e.g., cell differentiation or promoter activation.As a non-limiting example, cells from an established cell line canexpress one or more exogenous BoNT/A receptors by transient or stablytransfection of a polynucleotide molecule encoding a BoNT/A receptor,such as, e.g., a FGFR2, a FGFR3, or a SV2. As another non-limitingexample, cells from an established cell line can express one or moreexogenous BoNT/A receptors by protein transfection of the BoNT/Areceptors, such as, e.g., a FGFR2, a FGFR3, or a SV2. An exogenousBoNT/A receptor can be a naturally-occurring BoNT/A receptor ornaturally occurring variants thereof, or non-naturally occurring BoNT/Areceptor or non-naturally occurring variants thereof.

Thus in an embodiment, cells from an established cell line express anendogenous BoNT/A receptor. In aspects of this embodiment, theendogenous BoNT/A receptor expressed by cells from an established cellline is a naturally-occurring BoNT/A receptor. In other aspects of thisembodiment, the endogenous BoNT/A receptor expressed by cells from anestablished cell line is SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27,SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO:59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63, SEQ IDNO: 64, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 68, SEQID NO: 69, or SEQ ID NO: 70. In yet aspects of this embodiment, theendogenous BoNT/A receptor expressed by cells from an established cellline is a naturally occurring BoNT/A receptor, such as, e.g., a BoNT/Areceptor isoform or a BoNT/A receptor subtype. In other aspects of thisembodiment, the endogenous BoNT/A receptor expressed by cells from anestablished cell line is a naturally occurring BoNT/A receptor having,e.g., at least 70% amino acid identity, at least 75%, at least 80%, atleast 85%, at least 90%, or at least 95% amino acid identity with SEQ IDNO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQID NO: 30, SEQ ID NO: 31, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61,SEQ ID NO: 62, SEQ ID NO: 63, SEQ ID NO: 64, SEQ ID NO: 65, SEQ ID NO:66, SEQ ID NO: 67, SEQ ID NO: 68, SEQ ID NO: 69, or SEQ ID NO: 70.

In another embodiment, cells from an established cell line aretransiently or stably engineered to express an exogenous BoNT/Areceptor. In an aspect of this embodiment, cells from an establishedcell line are transiently or stably engineered to express anaturally-occurring BoNT/A receptor. In other aspects of thisembodiment, cells from an established cell line are transiently orstably engineered to express the naturally-occurring BoNT/A receptor ofSEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO:29, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO: 59, SEQ ID NO: 60, SEQ IDNO: 61, SEQ ID NO: 62, SEQ ID NO: 63, SEQ ID NO: 64, SEQ ID NO: 65, SEQID NO: 66, SEQ ID NO: 67, SEQ ID NO: 68, SEQ ID NO: 69, or SEQ ID NO:70. In yet other aspects of this embodiment, cells from an establishedcell line are transiently or stably engineered to express a naturallyoccurring BoNT/A receptor, such as, e.g., a BoNT/A receptor isoform or aBoNT/A receptor subtype. In still other aspects of this embodiment,cells from an established cell line are transiently or stably engineeredto express a naturally occurring BoNT/A receptor having, e.g., at least70% amino acid identity, at least 75%, at least 80%, at least 85%, atleast 90%, or at least 95% amino acid identity with SEQ ID NO: 25, SEQID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30,SEQ ID NO: 31, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO:62, SEQ ID NO: 63, SEQ ID NO: 64, SEQ ID NO: 65, SEQ ID NO: 66, SEQ IDNO: 67, SEQ ID NO: 68, SEQ ID NO: 69, or SEQ ID NO: 70.

In another aspect of the embodiment, cells from an established cell lineare transiently or stably engineered to express a non-naturallyoccurring BoNT/A receptor. In other aspects of this embodiment, cellsfrom an established cell line are transiently or stably engineered toexpress a non-naturally occurring BoNT/A receptor having, e.g., at least70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least95% amino acid identity with SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO:27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQ IDNO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63, SEQID NO: 64, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO: 68,SEQ ID NO: 69, or SEQ ID NO: 70. In other aspects of this embodiment,cells from an established cell line are transiently or stably engineeredto express a non-naturally occurring BoNT/A receptor having, e.g., 1 ormore, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more,8 or more, 9 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50or more, or 100 or more non-contiguous amino acid substitutions,deletions, or additions relative to SEQ ID NO: 25, SEQ ID NO: 26, SEQ IDNO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62, SEQ ID NO: 63,SEQ ID NO: 64, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO: 67, SEQ ID NO:68, SEQ ID NO: 69, or SEQ ID NO: 70. In yet other aspects of thisembodiment, cells from an established cell line are transiently orstably engineered to express a non-naturally occurring BoNT/A receptorhaving, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6or more, 7 or more, 8 or more, 9 or more, 10 or more, 20 or more, 30 ormore, 40 or more, 50 or more, or 100 or more contiguous amino acidsubstitutions, deletions, or additions relative to SEQ ID NO: 25, SEQ IDNO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQID NO: 31, SEQ ID NO: 59, SEQ ID NO: 60, SEQ ID NO: 61, SEQ ID NO: 62,SEQ ID NO: 63, SEQ ID NO: 64, SEQ ID NO: 65, SEQ ID NO: 66, SEQ ID NO:67, SEQ ID NO: 68, SEQ ID NO: 69, or SEQ ID NO: 70

In another embodiment, cells from an established cell line aretransiently or stably engineered to express an exogenous FGFR2, anexogenous FGFR3, an exogenous SV2, or any combination thereof. Inaspects of this embodiment, cells from an established cell line aretransiently or stably engineered to express a naturally-occurring FGFR2,a naturally-occurring FGFR3, a naturally-occurring SV2, or anycombination thereof. In yet other aspects of this embodiment, cells froman established cell line are transiently or stably engineered to expressa non-naturally-occurring FGFR2, a non-naturally-occurring FGFR3, anon-naturally-occurring SV2, or any combination thereof. In still otheraspects of this embodiment, cells from an established cell line aretransiently or stably engineered to express either a naturally-occurringFGFR2 or a non-naturally-occurring FGFR2, a naturally-occurring FGFR3 ora non-naturally-occurring FGFR3, a naturally-occurring SV2 or anon-naturally-occurring SV2, or any combination thereof.

Cells that express one or more endogenous or exogenous BoNT/A receptorscan be identified by routine methods including direct and indirectassays for toxin uptake. Assays that determine BoNT/A binding or uptakeproperties can be used to assess whether a cell is expressing a BoNT/Areceptor. Such assays include, without limitation, cross-linking assaysusing labeled BoNT/A, such as, e.g., [1251] BoNT/A, [1251], see, e.g.,Noriko Yokosawa et al., Binding of Clostridium botulinum type Cneurotoxin to different neuroblastoma cell lines, 57(1) Infect. Immun.272-277 (1989); Noriko Yokosawa et al., Binding of botulinum type Cl, Dand E neurotoxins to neuronal cell lines and synaptosomes, 29(2) Toxicon261-264 (1991); and Tei-ichi Nishiki et al., Identification of proteinreceptor for Clostridium botulinum type B neurotoxin in rat brainsynaptosomes, 269(14) J. Biol. Chem. 10498-10503 (1994). Othernon-limiting assays include immunocytochemical assays that detect BoNT/Abinding using labeled or unlabeled antibodies, see, e.g., AtsushiNishikawa et al., The receptor and transporter for internalization ofClostridium botulinum type C progenitor toxin into HT-29 cells, 319(2)Biochem. Biophys. Res. Commun. 327-333 (2004) and immunoprecipitationassays, see, e.g., Yukako Fujinaga et al., Molecular characterization ofbinding subcomponents of Clostridium botulinum type C progenitor toxinfor intestinal epithelial cells and erythrocytes, 150(Pt 5) Microbiology1529-1538 (2004), that detect bound toxin using labeled or unlabeledantibodies. Antibodies useful for these assays include, withoutlimitation, antibodies selected against BoNT/A, antibodies selectedagainst a BoNT/A receptor, such as, e.g., FGFR2, FGFR3, or SV2, and/orantibodies selected against a ganglioside, such as, e.g., GD1a, GD1b,GD3, GQ1b, or GT1b. If the antibody is labeled, the binding of themolecule can be detected by various means, including Western blotanalysis, direct microscopic observation of the cellular location of theantibody, measurement of cell or substrate-bound antibody following awash step, flow cytometry, electrophoresis or capillary electrophoresis,employing techniques well-known to those of skill in the art. If theantibody is unlabeled, one may employ a labeled secondary antibody forindirect detection of the bound molecule, and detection can proceed asfor a labeled antibody. It is understood that these and similar assaysthat determine BoNT/A uptake properties or characteristics can be usefulin identifying cells expressing endogenous or exogenous or BoNT/Areceptors.

Assays that monitor the release of a molecule after exposure to BoNT/Acan also be used to assess whether a cell is expressing one or moreendogenous or exogenous BoNT/A receptors. In these assays, inhibition ofthe molecule's release would occur in cells expressing a BoNT/A receptorafter BoNT/A treatment. Well known assays include methods that measureinhibition of radio-labeled catecholamine release from neurons, such as,e.g., [3H] noradrenaline or [3H] dopamine release, see e.g., A Fassio etal., Evidence for calcium-dependent vesicular transmitter releaseinsensitive to tetanus toxin and botulinum toxin type F, 90(3)Neuroscience 893-902 (1999); and Sara Stigliani et al., The sensitivityof catecholamine release to botulinum toxin C1 and E suggests selectivetargeting of vesicles set into the readily releasable pool, 85(2) J.Neurochem. 409-421 (2003), or measures catecholamine release using afluorometric procedure, see, e.g., Anton de Paiva et al., A role for theinterchain disulfide or its participating thiols in the internalizationof botulinum neurotoxin A revealed by a toxin derivative that binds toecto-acceptors and inhibits transmitter release intracellularly, 268(28)J. Biol. Chem. 20838-20844 (1993); Gary W. Lawrence et al., Distinctexocytotic responses of intact and permeabilized chromaffin cells aftercleavage of the 25-kDa synaptosomal-associated protein (SNAP-25) orsynaptobrevin by botulinum toxin A or B, 236(3) Eur. J. Biochem. 877-886(1996); and Patrick Foran et al., Botulinum neurotoxin C1 cleaves bothsyntaxin and SNAP-25 in intact and permeabilized chromaffin cells:correlation with its blockade of catecholamine release, 35(8)Biochemistry 2630-2636 (1996). Other non-limiting examples includeassays that measure inhibition of hormone release from endocrine cells,such as, e.g., anterior pituitary cells or ovarian cells. It isunderstood that these and similar assays for molecule release can beuseful in identifying cells expressing endogenous or exogenous or BoNT/Areceptors.

Assays that detect the cleavage of a BoNT/A substrate after exposure toa BoNT/A can also be used to assess whether a cell is expressing one ormore endogenous or exogenous BoNT/A receptors. In these assays,generation of a BoNT/A substrate cleavage-product, or disappearance ofthe intact BoNT/A substrate, would be detected in cells expressing aBoNT/A receptor after BoNT/A treatment. Non-limiting examples ofspecific Western blot analysis, as well as well-characterized reagents,conditions and protocols are readily available from commercial vendorsthat include, without limitation, Amersham Biosciences, Piscataway,N.J.; Bio-Rad Laboratories, Hercules, Calif.; Pierce Biotechnology,Inc., Rockford, Ill.; Promega Corporation, Madison, Wis., andStratagene, Inc., La Jolla, Calif. It is understood that these andsimilar assays for BoNT/A substrate cleavage can be useful inidentifying cells expressing endogenous or exogenous BoNT/A receptors.

As non-limiting examples, Western blot analysis using an antibody thatrecognizes BoNT/A SNAP-25-cleaved product or both the cleaved anduncleaved forms of SNAP-25 can be used to assay for uptake of BoNT/A.Examples of α-SNAP-25 antibodies useful for these assays include,without limitation, SMI-81 α-SNAP-25 mouse monoclonal antibody(Sternberger Monoclonals Inc., Lutherville, Md.), CI 71.1 mouseα-SNAP-25 monoclonal antibody (Synaptic Systems, Goettingen, Germany),CI 71.2 α-SNAP-25 mouse monoclonal antibody (Synaptic Systems,Goettingen, Germany), SP12 α-SNAP-25 mouse monoclonal antibody (Abcam,Cambridge, Mass.), α-SNAP-25 rabbit polyclonal antiserum (SynapticSystems, Goettingen, Germany), α-SNAP-25 rabbit polyclonal antiserumS9684 (Sigma, St. Louis, Mo.), and α-SNAP-25 rabbit polyclonal antiserum(Abcam, Cambridge, Mass.).

Aspects of the present disclosure provide cells that through geneticmanipulation or recombinant engineering are made to expresses anexogenous SNAP-25 and/or one or more exogenous BoNT/A receptors. Cellsuseful to express an exogenous SNAP-25 and/or one or more exogenousBoNT/A receptors through genetic manipulation or recombinant engineeringinclude neuronal cells and non-neuronal cells that may or may notexpress an endogenous SNAP-25 and/or one or more endogenous BoNT/Areceptors. It is further understood that such genetically manipulated orrecombinantly engineered cells may express an exogenous SNAP-25 and oneor more exogenous BoNT/A receptors under control of a constitutive,tissue-specific, cell-specific or inducible promoter element, enhancerelement or both. It is understood that any cell is useful as long as thecell can be genetically manipulated or recombinantly engineered toexpresses an exogenous SNAP-25 and/or one or more exogenous BoNT/Areceptors and is capable of undergoing BoNT/A intoxication.

Methods useful for introducing into a cell an exogenous polynucleotidemolecule encoding a component necessary for the cells to undergo theoverall cellular mechanism whereby a BoNT/A proteolytically cleaves aSNAP-25 substrate, such as, e.g., a SNAP-25, a FGFR2, a FGFR3, or a SV2,include, without limitation, chemical-mediated delivery methods, suchas, e.g., calcium phosphate-mediated, diethyl-aminoethyl (DEAE)dextran-mediated, lipid-mediated, polyethyleneimine (PEI)-mediated,polylysine-mediated and polybrene-mediated; physical-mediated deliverymethods, such as, e.g., biolistic particle delivery, microinjection,protoplast fusion and electroporation; and viral-mediated deliverymethods, such as, e.g., retroviral-mediated transfection, see e.g.,Introducing Cloned Genes into Cultured Mammalian Cells, pp. 16.1-16.62(Sambrook & Russell, eds., Molecular Cloning A Laboratory Manual, Vol.3, 3^(rd) ed. 2001); Alessia Colosimo et al., Transfer and Expression ofForeign Genes in Mammalian Cells, 29(2) Biotechniques 314-318, 320-322,324 (2000); Philip Washbourne & A. Kimberley McAllister, Techniques forGene Transfer into Neurons, 12(5) Curr. Opin. Neurobiol. 566-573 (2002);and Current Protocols in Molecular Biology, John Wley and Sons, pp9.16.4-9.16.11 (2000), each of which is incorporated by reference in itsentirety. One skilled in the art understands that selection of aspecific method to introduce a polynucleotide molecule into a cell willdepend, in part, on whether the cell will transiently or stably containa component necessary for the cells to undergo the overall cellularmechanism whereby a BoNT/A proteolytically cleaves a SNAP-25 substrate.Non-limiting examples of polynucleotide molecule encoding a componentnecessary for the cells to undergo the overall cellular mechanismwhereby a BoNT/A proteolytically cleaves a SNAP-25 substrate as asfollows: FGFR2 polynucleotide molecule of SEQ ID NO: 130, SEQ ID NO:131, SEQ ID NO: 132, SEQ ID NO: 133, SEQ ID NO: 134, SEQ ID NO: 135, SEQID NO: 136, SEQ ID NO: 137, or SEQ ID NO: 138; FGFR3 polynucleotidemolecule of SEQ ID NO: 139, SEQ ID NO: 140, or SEQ ID NO: 141; SV2polynucleotide molecule of SEQ ID NO: 142, SEQ ID NO: 143, or SEQ ID NO:144; and SNAP-25 polynucleotide molecule of SEQ ID NO: 145, or SEQ IDNO: 146.

Chemical-mediated delivery methods are well-known to a person ofordinary skill in the art and are described in, e.g., Martin Jordan &Florian Worm, Transfection of Adherent and Suspended Cells by CalciumPhosphate, 33(2) Methods 136-143 (2004); Chun Zhang et al.,Polyethylenimine Strategies for Plasmid Delivery to Brain-Derived Cells,33(2) Methods 144-150 (2004), each of which is hereby incorporated byreference in its entirety. Such chemical-mediated delivery methods canbe prepared by standard procedures and are commercially available, see,e.g., CellPhect Transfection Kit (Amersham Biosciences, Piscataway,N.J.); Mammalian Transfection Kit, Calcium phosphate and DEAE Dextran,(Stratagene, Inc., La Jolla, Calif.); Lipofectamine™ TransfectionReagent (Invitrogen, Inc., Carlsbad, Calif.); ExGen 500 Transfection kit(Fermentas, Inc., Hanover, Md.), and SuperFect and EffecteneTransfection Kits (Qiagen, Inc., Valencia, Calif.).

Physical-mediated delivery methods are well-known to a person ofordinary skill in the art and are described in, e.g., Jeike E. Biewengaet al., Plasmid-Mediated Gene Transfer in Neurons using the BiolisticsTechnique, 71(1) J. Neurosci. Methods. 67-75 (1997); John O'Brien &Sarah C. R. Lummis, Biolistic and Diolistic Transfection: Using the GeneGun to Deliver DNA and Lipophilic Dyes into Mammalian Cells, 33(2)Methods 121-125 (2004); M. Golzio et al., In Vitro and In Vivo ElectricField-Mediated Permeabilization, Gene Transfer, and Expression, 33(2)Methods 126-135 (2004); and Oliver Gresch et al., New Non-Viral Methodfor Gene Transfer into Primary Cells, 33(2) Methods 151-163 (2004), eachof which is hereby incorporated by reference in its entirety.

Viral-mediated delivery methods are well-known to a person of ordinaryskill in the art and are described in, e.g., Chooi M. Lai et al.,Adenovirus and Adeno-Associated Virus Vectors, 21(12) DNA Cell Biol.895-913 (2002); Ilya Frolov et al., Alphavirus-Based Expression Vectors:Strategies and Applications, 93(21) Proc. Natl. Acad. Sci. U.S.A11371-11377 (1996); Roland Wolkowicz et al., Lentiviral Vectors for theDelivery of DNA into Mammalian Cells, 246 Methods Mol. Biol. 391-411(2004); A. Huser & C. Hofmann, Baculovirus Vectors: Novel Mammalian CellGene-Delivery Vehicles and Their Applications, 3(1) Am. J.Pharmacogenomics 53-63 (2003); Tiziana Tonini et al., TransientProduction of Retroviral-and Lentiviral-Based Vectors for theTransduction of Mammalian Cells, 285 Methods Mol. Biol. 141-148 (2004);Manfred Gossen & Hermann Bujard, Tight Control of Gene Expression inEukaryotic Cells by Tetracycline-Responsive Promoters, U.S. Pat. No.5,464,758; Hermann Bujard & Manfred Gossen, Methods for Regulating GeneExpression, U.S. Pat. No. 5,814,618; David S. Hogness, PolynucleotidesEncoding Insect Steroid Hormone Receptor Polypeptides and CellsTransformed With Same, U.S. Pat. No. 5,514,578; David S. Hogness,Polynucleotide Encoding Insect Ecdysone Receptor, U.S. Pat. No.6,245,531; Elisabetta Vegeto et al., Progesterone Receptor Having C.Terminal Hormone Binding Domain Truncations, U.S. Pat. No. 5,364,791;Elisabetta Vegeto et al., Mutated Steroid Hormone Receptors, Methods forTheir Use and Molecular Switch for Gene Therapy, U.S. Pat. No.5,874,534, each of which is hereby incorporated by reference in itsentirety. Such viral-mediated delivery methods can be prepared bystandard procedures and are commercially available, see, e.g.,ViraPower™ Adenoviral Expression System (Invitrogen, Inc., Carlsbad,Calif.) and ViraPower™ Adenoviral Expression System Instruction Manual25-0543 version A, Invitrogen, Inc., (Jul. 15, 2002); and AdEasy™Adenoviral Vector System (Stratagene, Inc., La Jolla, Calif.) andAdEasy™ Adenoviral Vector System Instruction Manual 064004f, Stratagene,Inc. Furthermore, such viral delivery systems can be prepared bystandard methods and are commercially available, see, e.g., BD™ Tet-Offand Tet-On Gene Expression Systems (BD Biosciences-Clonetech, Palo Alto,Calif.) and BD™ Tet-Off and Tet-On Gene Expression Systems User Manual,PT3001-1, BD Biosciences Clonetech, (Mar. 14, 2003), GeneSwitch™ System(Invitrogen, Inc., Carlsbad, Calif.) and GeneSwitch™ System AMifepristone-Regulated Expression System for Mammalian Cells version D,25-0313, Invitrogen, Inc., (Nov. 4, 2002); ViraPower™ LentiviralExpression System (Invitrogen, Inc., Carlsbad, Calif.) and ViraPower™Lentiviral Expression System Instruction Manual 25-0501 version E,Invitrogen, Inc., (Dec. 8, 2003); and Complete Control® RetroviralInducible Mammalian Expression System (Stratagene, La Jolla, Calif.) andComplete Control® Retroviral Inducible Mammalian Expression SystemInstruction Manual, 064005e.

Thus, in an embodiment, cells from an established cell line susceptibleto BoNT/A intoxication transiently contain a polynucleotide moleculeencoding a component necessary for the cells to undergo the overallcellular mechanism whereby a BoNT/A proteolytically cleaves a SNAP-25substrate. In another embodiment, cells from an established cell linesusceptible to BoNT/A intoxication transiently contain a polynucleotidemolecule encoding a plurality of components necessary for the cells toundergo the overall cellular mechanism whereby a BoNT/A proteolyticallycleaves a SNAP-25 substrate. In aspects of this embodiment, cells froman established cell line susceptible to BoNT/A intoxication transientlycontain a polynucleotide molecule encoding FGFR2, FGFR3, SV2 or SNAP-25.In aspects of this embodiment, cells from an established cell linesusceptible to BoNT/A intoxication transiently contain thepolynucleotide molecule encoding FGFR2 of SEQ ID NO: 130, SEQ ID NO:131, SEQ ID NO: 132, SEQ ID NO: 133, SEQ ID NO: 134, SEQ ID NO: 135, SEQID NO: 136, SEQ ID NO: 137, or SEQ ID NO: 138. In other aspects of thisembodiment, cells from an established cell line susceptible to BoNT/Aintoxication transiently contain the polynucleotide molecule encodingFGFR3 of SEQ ID NO: 139, SEQ ID NO: 140, or SEQ ID NO: 141. In yet otheraspects of this embodiment, cells from an established cell linesusceptible to BoNT/A intoxication transiently contain thepolynucleotide molecule encoding SV2 of SEQ ID NO: 142, SEQ ID NO: 143,or SEQ ID NO: 144. In yet other aspects of this embodiment, cells froman established cell line susceptible to BoNT/A intoxication transientlycontain the polynucleotide molecule encoding SNAP-25 of SEQ ID NO: 145,or SEQ ID NO: 146.

In another embodiment, cells from an established cell line susceptibleto BoNT/A intoxication stably contain a polynucleotide molecule encodinga component necessary for the cells to undergo the overall cellularmechanism whereby a BoNT/A proteolytically cleaves a SNAP-25 substrate.In another embodiment, cells from an established cell line susceptibleto BoNT/A intoxication stably contain a polynucleotide molecule encodinga plurality of components necessary for the cells to undergo the overallcellular mechanism whereby a BoNT/A proteolytically cleaves a SNAP-25substrate. In aspects of this embodiment, cells from an established cellline susceptible to BoNT/A intoxication stably contain a polynucleotidemolecule encoding FGFR2, FGFR3, SV2 or SNAP-25. In aspects of thisembodiment, cells from an established cell line susceptible to BoNT/Aintoxication stably contain the polynucleotide molecule encoding FGFR2of SEQ ID NO: 130, SEQ ID NO: 131, SEQ ID NO: 132, SEQ ID NO: 133, SEQID NO: 134, SEQ ID NO: 135, SEQ ID NO: 136, SEQ ID NO: 137, or SEQ IDNO: 138. In other aspects of this embodiment, cells from an establishedcell line susceptible to BoNT/A intoxication stably contain thepolynucleotide molecule encoding FGFR3 of SEQ ID NO: 139, SEQ ID NO:140, or SEQ ID NO: 141. In yet other aspects of this embodiment, cellsfrom an established cell line susceptible to BoNT/A intoxication stablycontain the polynucleotide molecule encoding SV2 of SEQ ID NO: 142, SEQID NO: 143, or SEQ ID NO: 144. In yet other aspects of this embodiment,cells from an established cell line susceptible to BoNT/A intoxicationstably contain the polynucleotide molecule encoding SNAP-25 of SEQ IDNO: 145, or SEQ ID NO: 146.

As mentioned above, an exogenous component necessary for the cells toundergo the overall cellular mechanism whereby a BoNT/A proteolyticallycleaves a SNAP-25 substrate, such as, e.g., a SNAP-25, a FGFR2, a FGFR3,or a SV2 disclosed in the present specification can be introduced into acell. Any and all methods useful for introducing such an exogenouscomponent with a delivery agent into a cell population can be usefulwith the proviso that this method transiently introduces the exogenouscomponent disclosed in the present specification in at least 50% of thecells within a given cell population. Thus, aspects of this embodimentcan include a cell population in which, e.g., at least 50%, at least60%, at least 70%, at least 80%, or at least 90% of the given cellpopulation transiently contains an exogenous component necessary for thecells to undergo the overall cellular mechanism whereby a BoNT/Aproteolytically cleaves a SNAP-25 substrate, such as, e.g., a SNAP-25, aFGFR2, a FGFR3, or a SV2 disclosed in the present specification. As usedherein, the term “delivery agent” refers to any molecule that enables orenhances internalization of a covalently-linked, non-covalently-linkedor in any other manner associated with a polypeptide into a cell. Thus,the term “delivery agent” encompasses, without limitation, proteins,peptides, peptidomimetics, small molecules, polynucleotide molecules,liposomes, lipids, viruses, retroviruses and cells that, withoutlimitation, transport a covalently or non-covalently linked molecule tothe cell membrane, cell cytoplasm or nucleus. It further is understoodthat the term “delivery agent” encompasses molecules that areinternalized by any mechanism, including delivery agents which functionvia receptor mediated endocytosis and those which are independent ofreceptor mediated endocytosis.

A delivery agent can also be an agent that enables or enhances cellularuptake of a covalently linked component, like FGFR2, FGFR3, SV2, orSNAP-25, such as, e.g., by chemical conjugation or by geneticallyproduced fusion proteins. Methods that covalently link delivery agentsand methods of using such agents are described in, e.g., Steven F.Dowdy, Protein Transduction System and Methods of Use Thereof,International Publication No WO 00/34308; Gerard Chassaing & AlainProchiantz, Peptides which can be Used as Vectors for the IntracellularAddressing of Active Molecules, U.S. Pat. No. 6,080,724; Alan Frankel etal., Fusion Protein Comprising TAT-derived Transport Moiert, U.S. Pat.No. 5,674,980; Alan Frankel et al., TAT-derived Transport PolypeptideConjugates, U.S. Pat. No. 5,747,641; Alan Frankel et al., TAT-derivedTransport Polypeptides and Fusion Proteins, U.S. Pat. No. 5,804,604;Peter F. J. O'Hare et al., Use of Transport Proteins, U.S. Pat. No.6,734,167; Yao-Zhong Lin & Jack J. Hawiger, Method for ImportingBiologically Active Molecules into Cells, U.S. Pat. No. 5,807,746;Yao-Zhong Lin & Jack J. Hawiger, Method for Importing BiologicallyActive Molecules into Cells, U.S. Pat. No. 6,043,339; Yao-Zhong Lin etal., Sequence and Method for Genetic Engineering of Proteins with CellMembrane Translocating Activity, U.S. Pat. No. 6,248,558; Yao-Zhong Linet al., Sequence and Method for Genetic Engineering of Proteins withCell Membrane Translocating Activity, U.S. Pat. No. 6,432,680; Jack J.Hawiger et al., Method for Importing Biologically Active Molecules intoCells, U.S. Pat. No. 6,495,518; Yao-Zhong Lin et al., Sequence andMethod for Genetic Engineering of Proteins with Cell MembraneTranslocating Activity, U.S. Pat. No. 6,780,843; Jonathan B. Rothbard &Paul A Wender, Method and Composition for Enhancing Transport AcrossBiological Membranes, U.S. Pat. No. 6,306,993; Jonathan B. Rothbard &Paul A Wender, Method and Composition for Enhancing Transport AcrossBiological Membranes, U.S. Pat. No. 6,495,663; and Pamela B. Davis etal., Fusion Proteins for Protein Delivery, U.S. Pat. No. 6,287,817, eachof which is incorporated by reference in its entirety.

A delivery agent can also be an agent that enables or enhances cellularuptake of a non-covalently associated component, like FGFR2, FGFR3,SV2c, or SNAP-25. Methods that function in the absence of covalentlinkage and methods of using such agents are described in, e.g., GillesDivita et al, Peptide-Mediated Transfection Agents and Methods of Use,U.S. Pat. No. 6,841,535; Philip L Feigner and Olivier Zelphati,Intracellular Protein Delivery Compositions and Methods of Use, U.S.Patent Publication No. 2003/0008813; and Michael Karas, IntracellularDelivery of Small Molecules, Proteins and Nucleic Acids, U.S. PatentPublication 2004/0209797, each of which is incorporated by reference inits entirety. Such peptide delivery agents can be prepared and used bystandard methods and are commercially available, see, e.g. the CHARIOT™Reagent (Active Motif, Carlsbad, Calif.); BIO-PORTER® Reagent (GeneTherapy Systems, Inc., San Diego, Calif.), BIO TREK™ Protein DeliveryReagent (Stratagene, La Jolla, Calif.), and PRO-JECT™ ProteinTransfection Reagent (Pierce Biotechnology Inc., Rockford, Ill.).

Aspects of the present disclosure comprise, in part, a sample comprisinga BoNT/A. As used herein, the term “sample comprising a BoNT/A” refersto any biological matter that contains or potentially contains an activeBoNT/A. A variety of samples can be assayed according to a methoddisclosed in the present specification including, without limitation,purified, partially purified, or unpurified BoNT/A; recombinant singlechain or di-chain toxin with a naturally or non-naturally occurringsequence; recombinant BoNT/A with a modified protease specificity;recombinant BoNT/A with an altered cell specificity; bulk BoNT/A; aformulated BoNT/A product, including, e.g., BOTOX®, DYSPORT®/RELOXIN®,XEOMIN®, PURTOX®, NEURONOX®, BTX-A and; cells or crude, fractionated orpartially purified cell lysates from, e.g., bacteria, yeast, insect, ormammalian sources; blood, plasma or serum; raw, partially cooked,cooked, or processed foods; beverages; animal feed; soil samples; watersamples; pond sediments; lotions; cosmetics; and clinical formulations.It is understood that the term sample encompasses tissue samples,including, without limitation, mammalian tissue samples, livestocktissue samples such as sheep, cow and pig tissue samples; primate tissuesamples; and human tissue samples. Such samples encompass, withoutlimitation, intestinal samples such as infant intestinal samples, andtissue samples obtained from a wound. As non-limiting examples, a methodof detecting picomolar amounts of BoNT/A activity can be useful fordetermining the presence or activity of a BoNT/A in a food or beveragesample; to assay a sample from a human or animal, for example, exposedto a BoNT/A or having one or more symptoms of botulism; to followactivity during production and purification of bulk BoNT/A; to assay aformulated BoNT/A product used in pharmaceutical or cosmeticsapplications; or to assay a subject's blood serum for the presence orabsence of neutralizing α-BoNT/A antibodies.

Thus, in an embodiment, a sample comprising a BoNT/A is a samplecomprising any amount of a BoNT/A. In aspects of this embodiment, asample comprising a BoNT/A comprises about 100 ng or less, about 10 ngor less, about 1 ng or less, about 100 pg or less, about 10 pg or less,or about 1 pg or less of a BoNT/A. In other aspects of this embodiment,a sample comprising a BoNT/A comprises about 1 pM or less, about 100 nMor less, about 10 nM or less, about 1 nM or less, about 100 pM or less,about 10 pM or less, about 1 pM or less, about 100 fM or less, about 10fM or less, or about 1 fM or less of a BoNT/A.

Aspects of the present disclosure comprise, in part, isolating from thetreated cell a SNAP-25 component comprising a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond. As used herein, the term “SNAP-25 component comprising a SNAP-25having a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond” refers to a cellular component containing the SNAP-25cleavage product. It is envisioned that any method suitable forenriching or isolating a SNAP-25 component can be useful, including,without limitation, cell lysing protocols, spin-column purificationprotocols, immunoprecipitation, affinity purification, and proteinchromatography.

Aspects of the present disclosure comprise, in part, an α-SNAP-25antibody linked to a solid phase support. As used herein, the term“solid-phase support” is synonymous with “solid phase” and refers to anymatrix that can be used for immobilizing an α-SNAP-25 antibody disclosedin the present specification. Non-limiting examples of solid phasesupports include, e.g., a tube; a plate; a column; pins or “dipsticks”;a magnetic particle, a bead or other spherical or fibrouschromatographic media, such as, e.g., agarose, sepharose, silica andplastic; and sheets or membranes, such as, e.g., nitrocellulose andpolyvinylidene fluoride (PVDF). The solid phase support can beconstructed using a wide variety of materials such as, e.g., glass,carbon, polystyrene, polyvinylchloride, polypropylene, polyethylene,dextran, nylon, diazocellulose, or starch. The solid phase supportselected can have a physical property that renders it readily separablefrom soluble or unbound material and generally allows unbound materials,such as, e.g., excess reagents, reaction by-products, or solvents, to beseparated or otherwise removed (by, e.g., washing, filtration,centrifugation, etc.) from solid phase support-bound assay component.Non-limiting examples of how to make and use a solid phase supports aredescribed in, e.g., Molecular Cloning, A Laboratory Manual, supra,(2001); and Current Protocols in Molecular Biology, supra, (2004), eachof which is hereby incorporated by reference in its entirety.

Aspects of the present disclosure comprise, in part, detecting thepresence of an antibody-antigen complex comprising an α-SNAP-25 antibodythat selectively binds to a SNAP-25 epitope having a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond and aSNAP-25 cleavage product having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond. It is envisioned that anydetection system can be used to practice aspects of this disclosedimmuno-based method, with the provision that the signal to noise ratiocan distinguish to a statistically significant degree the signal fromthe antibody-antigen complex from the background signal. Non-limitingexamples of immuno-based detection systems include immunoblot analysis,like Western blotting and dot-blotting, immunoprecipitation analysis,enzyme-linked immunosorbent analysis (ELISA), and sandwich ELISA. Thedetection of the signal can be achieved using autoradiography withimaging or phosphorimaging (AU), chemiluminescense (CL),electrochemiluminescence (ECL), bioluminescence (BL), fluorescence,resonance energy transfer, plane polarization, colormetric, or flowcytometry (FC). Descriptions of immuno-based detection systems aredisclosed in, e.g., Michael M. Rauhut, Chemiluminescence, In Kirk-OthmerConcise Encyclopedia of Chemical Technology (Ed. Grayson, 3rd ed, JohnWley and Sons, 1985); A. W. Knight, A Review of Recent Trends inAnalytical Applications of Electrogenerated Chemiluminescence, TrendsAnal. Chem. 18(1): 47-62 (1999); K. A. Fahnrich, et al., RecentApplications of Electrogenerated Chemiluminescence sin ChemicalAnalysis, Talanta 54(4): 531-559 (2001); Commonly Used Techniques inMolecular Cloning, pp. A8.1-A8-55 (Sambrook & Russell, eds., MolecularCloning A Laboratory Manual, Vol. 3, 3^(rd) ed. 2001); DetectionSystems, pp. A9.1-A9-49 (Sambrook & Russell, eds., Molecular Cloning ALaboratory Manual, Vol. 3, 3^(rd) ed. 2001); ElectrogeneratedChemiluminescence, (Ed. Allen J. Bard, Marcel Dekker, Inc., 2004), eachof which is hereby incorporated by reference in its entirety.

A sandwich ELISA (or sandwich immunoassay) is a method based on twoantibodies, which bind to different epitopes on the antigen. A captureantibody having a high binding specificity for the antigen of interest,is bound to a solid surface. The antigen is then added followed byaddition of a second antibody referred to as the detection antibody. Thedetection antibody binds the antigen to a different epitope than thecapture antibody. The antigen is therefore ‘sandwiched’ between the twoantibodies. The antibody binding affinity for the antigen is usually themain determinant of immunoassay sensitivity. As the antigenconcentration increases the amount of detection antibody increasesleading to a higher measured response. To quantify the extent of bindingdifferent reporter systems can be used, such as, e.g., an enzymeattached to the secondary antibody and a reporter substrate where theenzymatic reaction forms a readout as the detection signal. The signalgenerated is proportional to the amount of target antigen present in thesample. The reporter substrate used to measure the binding eventdetermines the detection mode. A spectrophotometric plate reader is usedfor colorimetric detection. Chemiluminescent andelectrochemiluminescence substrates have been developed which furtheramplify the signal and can be read on a luminescent reader. The reportercan also be a fluorescent readout where the enzyme step of the assay isreplaced with a fluorophore and the readout is then measured using afluorescent reader. Reagents and protocols necessary to perform an ECLsandwich ELISA are commercially available, including, without exception,MSD sandwich ELISA-ECL detection platform (Meso Scale Discovery,Gaithersburg, Md.).

Thus, in an embodiment, detecting the presence of an antibody-antigencomplex comprising an α-SNAP-25 antibody that selectively binds to aSNAP-25 epitope having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond and a SNAP-25 cleavage product havinga carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond can be performed using an immuno-blot analysis, animmunoprecipitation analysis, an ELISA, or a sandwich ELISA. In aspectsof this embodiment, the detection is performed using a AU, CL, ECL, orBL immuno-blot analysis, a AU, CL, ECL, BL, or FC immunoprecipitationanalysis, a AU, CL, ECL, BL, or FC ELISA, or a AU, CL, ECL, BL, or FCsandwich ELISA.

Aspects of the present disclosure can be practiced in a singleplex ormultiplex fashion. An immuno-based method of detecting BoNT/A activitypracticed in a single-plex fashion is one that only detects the presenceof an antibody-antigen complex comprising an α-SNAP-25 antibody and aSNAP-25 cleavage product having a carboxyl-terminus at the P₁ residue ofthe BoNT/A cleavage site scissile bond. An immuno-based method ofdetecting BoNT/A activity practiced in a multiplex fashion is one thatconcurrently detects the presence of two or more antibody-antigencomplexes; one of which is the antibody-antigen complex comprising anα-SNAP-25 antibody and a SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond; and the other(s) of which is antibody-antigen complex to a second,third, fourth, etc. different protein. A second protein can be used,e.g., as an internal control to minimize sample to sample variability bynormalizing the amount of α-SNAP-25/SNAP-25 antibody-antigen complexdetected to the amount of antibody-antigen complex detected for thesecond protein. As such, the second protein is usually one that isconsistently expressed by the cell, such as a house-keeping protein.Non-limiting examples of a useful second protein, include, e.g., aGlyceraldehyde-3-Phosphate Dehydrogenase (GAPDH), Syntaxin, cytokines.Methods of performing an immuno-based assay in a multiplex fashion aredescribed in, e.g., U. B. Nielsen and B. H. Geierstanger, MultiplexedSandwich Assays in s, J. Immunol. Methods. 290(1-2): 107-120 2004); R.Barry and M, Soloviev, Quantitative Protein Profiling using AntibodyArrays, Proteomics, 4(12): 3717-3726 (2004); M. M. Ling et al.,Multiplexing Molecular Diagnostics and Immunoassays using EmergingMicroarray Technologies, Expert Rev Mol Diagn. 7(1): 87-98 (2007); S. X.Leng et al., ELISA and Multiplex Technologies for Cytokine Measurementin Inflammation and Aging Research, J Gerontol A Biol Sci Med Sci.63(8): 879-884 (2008), each of which is hereby incorporated by referencein its entirety.

Thus, in one embodiment, an immuno-based method of detecting BoNT/Aactivity practiced in a single-plex fashion by only detecting thepresence of an antibody-antigen complex comprising an α-SNAP-25 antibodyand a SNAP-25 cleavage product having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond. In anotherembodiment, immuno-based method of detecting BoNT/A activity practicedin a multiplex fashion by concurrently detecting the presence of anantibody-antigen complex comprising an α-SNAP-25 antibody and a SNAP-25cleavage product having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond and at least one otherantibody-antigen complex to a protein other than SNAP-25, such as, e.g.,GAPDH or Syntaxin.

Aspects of the present disclosure provide, in part, a method ofdetermining BoNT/A immunoresistance. As used herein, the term “BoNT/Aimmunoresistance” means a mammal that does not fully respond to a BoNT/Atherapy, or shows a reduced beneficial effect of a BoNT/A therapybecause the immune response of that mammal, either directly orindirectly, reduces the efficacy of the therapy. A non-limiting exampleof reduced efficacy would be the presence in a mammal of at least oneneutralizing α-BoNT/A antibody that binds to a BoNT/A toxin in a mannerthat reduces or prevents the specificity or activity of the toxin. Asused herein, the term “BoNT/A therapy” means a treatment, remedy, cure,healing, rehabilitation or any other means of counteracting somethingundesirable in a mammal requiring neuromodulation using a BoNT/A toxinor administering to a mammal one or more controlled doses of amedication, preparation or mixture of a BoNT/A toxin that has medicinal,therapeutic, curative, cosmetic, remedial or any other beneficialeffect. BoNT/A therapy encompasses, without limitation, the use of anynaturally occurring or modified fragment thereof, in any formulation,combined with any carrier or active ingredient and administered by anyroute of administration. An exemplary, well-known BoNT/A therapy is aBOTOX® therapy.

Aspects of the present disclosure provide, in part, a test sampleobtained from a mammal being tested for the presence or absence ofα-BoNT/A neutralizing antibodies. As used herein, the term “test sample”refers to any biological matter that contains or potentially contains atleast one α-BoNT/A antibody. An α-BoNT/A antibody can be a neutralizinganti-BoNT/A antibody or a non-neutralizing anti-BoNT/A antibody. As usedherein, the term “neutralizing anti-BoNT/A antibodies” means anyα-BoNT/A antibody that will, under physiological conditions, bind to aregion of a BoNT/A toxin in such a manner as to reduce or prevent thetoxin from exerting its effect in a BoNT/A therapy. As used herein, theterm “non-neutralizing α-BoNT/A antibodies” means any α-BoNT/A antibodythat will, under physiological conditions, bind to a region of a BoNT/Atoxin, but not prevent the toxin from exerting its effect in a BoNT/Atherapy. It is envisioned that any and all samples that can containα-BoNT/A antibodies can be used in this method, including, withoutlimitation, blood, plasma, serum and lymph fluid. In addition, any andall organisms capable of raising α-BoNT/A antibodies against a BoNT/Atoxin can serve as a source for a sample including, but not limited to,birds and mammals, including mice, rats, goats, sheep, horses, donkeys,cows, primates and humans. Non-limiting examples of specific protocolsfor blood collection and serum preparation are described in, e.g.,Marjorie Schaub Di Lorenzo & Susan King Strasinger, BLOOD COLLECTION INHEALTHCARE (F. A. Davis Company, 2001); and Diana Garza & KathleenBecan-McBride, PHLEBOTOMY HANDBOOK: BLOOD COLLECTION ESSENTIALS(Prentice Hall, 6^(th) ed., 2002). These protocols are routineprocedures well within the scope of one skilled in the art and from theteaching herein. A test sample can be obtained from an organism prior toexposure to a BoNT/A toxin, after a single BoNT/A treatment, aftermultiple BoNT/A toxin treatments, before onset of resistance to a BoNT/Atherapy, or after onset of resistance to a BoNT/A therapy.

Aspects of the present disclosure provide, in part, a control sample. Asused herein, the term “control sample” means any sample in which thepresence or absence of the test sample is known and includes bothnegative and positive control samples. Wth respect to neutralizingα-BoNT/A antibodies, a negative control sample can be obtained from anindividual who had never been exposed to BoNT/A and may include, withoutlimitation, a sample from the same individual supplying the test sample,but taken before undergoing a BoNT/A therapy; a sample taken from adifferent individual never been exposed to BoNT/A; a pooled sample takenfrom a plurality of different individuals never been exposed to BoNT/A.With respect to neutralizing α-BoNT/A antibodies, a positive controlsample can be obtained from an individual manifesting BoNT/Aimmunoresistance and includes, without limitation, individual testingpositive in a patient-based testing assays; individual testing positivein an in vivo bioassay; and individual showing hyperimmunity, e.g., aBoNT/A vaccinated individual.

It is further foreseen that α-BoNT/A antibodies can be purified from asample. Anti-BoNT/A antibodies can be purified from a sample, using avariety of procedures including, without limitation, Protein A/Gchromatography and affinity chromatography. Non-limiting examples ofspecific protocols for purifying antibodies from a sample are describedin, e.g., ANTIBODIES: A LABORATORY MANUAL (Edward Harlow & David Lane,eds., Cold Spring Harbor Laboratory Press, 2^(nd) ed. 1998); USINGANTIBODIES: A LABORATORY MANUAL: PORTABLE PROTOCOL No. I (Edward Harlow& David Lane, Cold Spring Harbor Laboratory Press, 1998); and MOLECULARCLONING, A LABORATORY MANUAL, supra, (2001), which are herebyincorporated by reference. In addition, non-limiting examples ofantibody purification methods as well as well-characterized reagents,conditions and protocols are readily available from commercial vendorsthat include, without limitation, Pierce Biotechnology, Inc., Rockford,Ill.; and Zymed Laboratories, Inc., South San Francisco, Calif. Theseprotocols are routine procedures well within the scope of one skilled inthe art.

Thus, in an embodiment, a sample comprises blood. In aspect of thisembodiment, the sample comprises mouse blood, rat blood, goat blood,sheep blood, horse blood, donkey blood, cow blood, primate blood orhuman blood. In another embodiment, a sample comprises plasma. In anaspect of this embodiment, a test sample comprises mouse plasma, ratplasma, goat plasma, sheep plasma, horse plasma, donkey plasma, cowplasma, primate plasma or human plasma. In another embodiment, a samplecomprises serum. In an aspect of this embodiment, the sample comprisesmouse serum, rat serum, goat serum, sheep serum, horse serum, donkeyserum, cow serum, primate serum and human serum. In another embodiment,a sample comprises lymph fluid. In aspect of this embodiment, a samplecomprises mouse lymph fluid, rat lymph fluid, goat lymph fluid, sheeplymph fluid, horse lymph fluid, donkey lymph fluid, cow lymph fluid,primate lymph fluid or human lymph fluid. In yet another embodiment, asample is a test sample. In yet another embodiment, a sample is acontrol sample. In aspects of this embodiment, a control sample is anegative control sample or a positive control sample.

Aspects of the present disclosure provide, in part, comparing the amountof SNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond detected in step (d) to the amount ofSNAP-25 having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond detected in step (e). In an embodiment, theamount of SNAP-25 cleavage product in the test sample is higher ascompared to the amount of SNAP-25 cleavage product in the controlsample. In an aspect of this embodiment, a higher amount of SNAP-25cleavage product in the test sample as compared to a positive controlsample indicates a reduction in or lack of BoNT/A immunoresistance inthe mammal. In another aspect of this embodiment, an equivalent amountof SNAP-25 cleavage product in the test sample as compared to a negativecontrol sample indicates a reduction in or lack of BoNT/Aimmunoresistance in the mammal. In another embodiment, the amount ofSNAP-25 cleavage product in the test sample is lower as compared to theamount of SNAP-25 cleavage product in the control sample. In an aspectof this embodiment, a lower or equivalent amount of SNAP-25 cleavageproduct in the test sample as compared to a positive control sampleindicates an increase in or presence of BoNT/A immunoresistance in themammal. In another aspect of this embodiment, a lower amount of SNAP-25cleavage product in the test sample as compared to a negative controlsample indicates an increase in or presence of BoNT/A immunoresistancein the mammal.

It is envisioned that any and all assay conditions suitable fordetecting the present of a neutralizing α-BoNT/A antibody in a sampleare useful in the methods disclosed in the present specification, suchas, e.g., linear assay conditions and non-linear assay conditions. In anembodiment, the assay conditions are linear. In an aspect of thisembodiment, the assay amount of a BoNT/A is in excess. In another aspectof this embodiment, the assay amount of a BoNT/A is rate-limiting. Inanother aspect of this embodiment, the assay amount of a test sample israte-limiting.

Aspects of the present disclosure can also be described as follows:

1. A composition comprising a carrier linked to a flexible linker linkedto SNAP-25 antigen having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond.

2. The composition of 1, wherein the the P₁ residue of the BoNT/Acleavage site scissile bond is glutamine or lysine.

3. The composition of 1, wherein the SNAP-25 antigen comprises SEQ IDNO: 147.

4. The composition of 1, wherein the flexible linker and the SNAP-25antigen amino acid sequence is SEQ ID NO: 38 or SEQ ID NO: 46.

5. An isolated α-SNAP-25 antibody, wherein the isolated α-SNAP-25antibody binds an eptiope comprising a carboxyl-terminus at the P₁residue from the BoNT/A cleavage site scissile bond from a SNAP-25cleavage product.

6. The isolated α-SNAP-25 antibody of 5, wherein the α-SNAP-25 antibodyhas an association rate constant for an epitope not comprising acarboxyl-terminus glutamine of the BoNT/A cleavage site scissile bondfrom a SNAP-25 cleavage product of less than 1×10¹ M⁻¹ s⁻¹; and whereinthe α-SNAP-25 antibody has an equilibrium disassociation constant forthe epitope of less than 0.450 nM.

7. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody has a heavy chain variable region comprising the amino acidsequence selected from the group consisting of SEQ ID NO: 72, SEQ ID NO:74, SEQ ID NO: 76, SEQ ID NO: 80, and SEQ ID NO: 82; and a light chainvariable region comprising the amino acid sequence selected from thegroup consisting of SEQ ID NO: 84, SEQ ID NO: 86, SEQ ID NO: 88, SEQ IDNO: 90, and SEQ ID NO: 92.

8. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody comprises at least the V_(H) CDR1 of SEQ ID NO: 93, the V_(H)CDR1 of SEQ ID NO: 94, the V_(H) CDR1 of SEQ ID NO: 95, the V_(H) CDR1of SEQ ID NO: 118, the V_(H) CDR1 of SEQ ID NO: 119, or the V_(H) CDR1of SEQ ID NO: 120.

9. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody comprises at least the V_(H) CDR2 of SEQ ID NO: 96, the V_(H)CDR2 of SEQ ID NO: 97, the V_(H) CDR2 of SEQ ID NO: 98, the V_(H) CDR2of SEQ ID NO: 99, the V_(H) CDR2 of SEQ ID NO: 121, the V_(H) CDR2 ofSEQ ID NO: 122, or the V_(H) CDR2 of SEQ ID NO: 123.

10. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody comprises at least the V_(H) CDR3 of SEQ ID NO: 100, the V_(H)CDR3 of SEQ ID NO: 101, the V_(H) CDR3 of SEQ ID NO: 102, or the V_(H)CDR3 of SEQ ID NO: 124.

11. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody comprises at least the V_(L) CDR1 of SEQ ID NO: 103, the V_(L)CDR1 of SEQ ID NO: 104, the V_(L) CDR1 of SEQ ID NO: 105, the V_(L) CDR1of SEQ ID NO: 106, the V_(L) CDR1 of SEQ ID NO: 107, the V_(L) CDR1 ofSEQ ID NO: 125, the V_(L) CDR1 of SEQ ID NO: 126, the V_(L) CDR1 of SEQID NO: 127, the V_(L) CDR1 of SEQ ID NO: 128, or the V_(L) CDR1 of SEQID NO: 129.

12. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody comprises at least the V_(L) CDR2 of SEQ ID NO: 108, the V_(L)CDR2 of SEQ ID NO: 109, the V_(L) CDR2 of SEQ ID NO: 110, the V_(L) CDR2of SEQ ID NO: 111, or the V_(L) CDR2 of SEQ ID NO: 112.

13. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody comprises at least the V_(L) CDR3 of SEQ ID NO: 113, the V_(L)CDR3 of SEQ ID NO: 114, the V_(L) CDR3 of SEQ ID NO: 115, the V_(L) CDR3of SEQ ID NO: 116, or the V_(L) CDR3 of SEQ ID NO: 117.

14. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody comprises a heavy chain variable region comprising SEQ ID NO:93, SEQ ID NO: 121 and SEQ ID NO: 100; and a light chain variable regioncomprising SEQ ID NO: 105, SEQ ID NO: 110 and SEQ ID NO: 115.

15. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody selectively binds the SNAP-25 epitope of SEQ ID NO: 32, SEQ IDNO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQID NO: 147 or SEQ ID NO: 148.

16. The isolated α-SNAP-25 antibody of 5, wherein the isolated α-SNAP-25antibody selectively binds the SNAP-25 epitope of SEQ ID NO: 39, SEQ IDNO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, or SEQ ID NO: 44.

17. A method of detecting BoNT/A activity, the method comprising thesteps of: a) treating a cell from an established cell line with a samplecomprising a BoNT/A, wherein the cell from an established cell line issusceptible to BoNT/A intoxication by a BoNT/A; b) isolating from thetreated cell a SNAP-25 component comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond; c) contacting the SNAP-25 component with an α-SNAP-25antibody, wherein the α-SNAP-25 antibody binds an eptiope comprising acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond from a SNAP-25 cleavage product; and d) detecting the presence ofan antibody-antigen complex comprising the α-SNAP-25 antibody and theSNAP-25 cleavage product; wherein detection by the antibody-antigencomplex is indicative of BoNT/A activity.

18. A method of detecting BoNT/A activity, the method comprising thesteps of: a) treating a cell from an established cell line with a samplecomprising a BoNT/A, wherein the cell from an established cell line issusceptible to BoNT/A intoxication by a BoNT/A; b) isolating from thetreated cell a SNAP-25 component comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond; c) contacting the SNAP-25 component with an α-SNAP-25antibody linked to a solid phase support, wherein the α-SNAP-25 antibodybinds an eptiope comprising a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond from a SNAP-25 cleavage product; andd) detecting the presence of an antibody-antigen complex comprising theα-SNAP-25 antibody and the SNAP-25 cleavage product; wherein detectionby the antibody-antigen complex is indicative of BoNT/A activity.

19. A method of detecting BoNT/A activity, the method comprising thesteps of: a) treating a cell from an established cell line with a samplecomprising a BoNT/A, wherein the cell from an established cell line issusceptible to BoNT/A intoxication by a BoNT/A; b) isolating from thetreated cell a SNAP-25 component comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond; c) fixing the SNAP-25 component to a solid phase support;d) contacting the SNAP-25 component with an α-SNAP-25 antibody, whereinthe α-SNAP-25 antibody binds an eptiope comprising a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond from aSNAP-25 cleavage product; and e) detecting the presence of anantibody-antigen complex comprising the α-SNAP-25 antibody and theSNAP-25 cleavage product; wherein detection by the antibody-antigencomplex is indicative of BoNT/A activity.

20. A method of detecting BoNT/A activity, the method comprising thesteps of: a) treating a cell from an established cell line with a samplecomprising a BoNT/A, wherein the cell from an established cell line canuptake BoNT/A; b) isolating from the treated cell a SNAP-25 componentcomprising a SNAP-25 cleavage product having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond; c) contacting theSNAP-25 component with an α-SNAP-25 antibody, wherein the α-SNAP-25antibody binds an eptiope comprising a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond from a SNAP-25cleavage product; and d) detecting the presence of an antibody-antigencomplex comprising the α-SNAP-25 antibody and the SNAP-25 cleavageproduct; wherein detection by the antibody-antigen complex is indicativeof BoNT/A activity.

21. A method of detecting BoNT/A activity, the method comprising thesteps of: a) treating a cell from an established cell line with a samplecomprising a BoNT/A, wherein the cell from an established cell line canuptake BoNT/A; b) isolating from the treated cell a SNAP-25 componentcomprising a SNAP-25 cleavage product having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond; c) contacting theSNAP-25 component with an α-SNAP-25 antibody linked to a solid phasesupport, wherein the α-SNAP-25 antibody binds an eptiope comprising acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond from a SNAP-25 cleavage product; and d) detecting the presence ofan antibody-antigen complex comprising the α-SNAP-25 antibody and theSNAP-25 cleavage product; wherein detection by the antibody-antigencomplex is indicative of BoNT/A activity.

22. A method of detecting BoNT/A activity, the method comprising thesteps of: a) treating a cell from an established cell line with a samplecomprising a BoNT/A, wherein the cell from an established cell line canuptake BoNT/A; b) isolating from the treated cell a SNAP-25 componentcomprising a SNAP-25 cleavage product having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond; c) fixing theSNAP-25 component to a solid phase support; d) contacting the SNAP-25component with an α-SNAP-25 antibody, wherein the α-SNAP-25 antibodybinds an eptiope comprising a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond from a SNAP-25 cleavage product; ande) detecting the presence of an antibody-antigen complex comprising theα-SNAP-25 antibody and the SNAP-25 cleavage product; wherein detectionby the antibody-antigen complex is indicative of BoNT/A activity.

23. A method of determining BoNT/A immunoresistance in a mammalcomprising the steps of: a) adding a BoNT/A to a test sample obtainedfrom a mammal being tested for the presence or absence of α-BoNT/Aneutralizing antibodies; b) treating a cell from an established cellline with the test sample, wherein the cell from an established cellline is susceptible to BoNT/A intoxication; c) isolating from thetreated cells a SNAP-25 component comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond; d) contacting the SNAP-25 component with an α-SNAP-25antibody, wherein the α-SNAP-25 antibody binds an eptiope comprising acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond from a SNAP-25 cleavage product; e) detecting the presence of anantibody-antigen complex comprising the α-SNAP-25 antibody and theSNAP-25 cleavage product; f) repeating steps b-e with a negative controlsample instead of a test sample, the negative control sample comprisinga BoNT/A and a serum known not to contain α-BoNT/A neutralizingantibodies; and g) comparing the amount of antibody-antigen complexdetected in step e to the amount of antibody-antigen complex detected instep f, wherein detection of a lower amount of antibody-antigen complexdetected in step e relative to the amount of antibody-antigen complexdetected in step f is indicative of the presence of α-BoNT/Aneutralizing antibodies.

24. A method of determining BoNT/A immunoresistance in a mammalcomprising the steps of: a) adding a BoNT/A to a test sample obtainedfrom a mammal being tested for the presence or absence of α-BoNT/Aneutralizing antibodies; b) treating a cell from an established cellline with the test sample, wherein the cell from an established cellline is susceptible to BoNT/A intoxication; c) isolating from thetreated cells a SNAP-25 component comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond; d) contacting the SNAP-25 component with an α-SNAP-25antibody linked to a solid phase support, wherein the α-SNAP-25 antibodybinds an eptiope comprising a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond from a SNAP-25 cleavage product; e)detecting the presence of an antibody-antigen complex comprising theα-SNAP-25 antibody and the SNAP-25 cleavage product; f) repeating stepsb-e with a negative control sample instead of a test sample, thenegative control sample comprising a BoNT/A and a serum known not tocontain α-BoNT/A neutralizing antibodies; and g) comparing the amount ofantibody-antigen complex detected in step e to the amount ofantibody-antigen complex detected in step f, wherein detection of alower amount of antibody-antigen complex detected in step e relative tothe amount of antibody-antigen complex detected in step f is indicativeof the presence of α-BoNT/A neutralizing antibodies.

25. A method of determining BoNT/A immunoresistance in a mammalcomprising the steps of: a) adding a BoNT/A to a test sample obtainedfrom a mammal being tested for the presence or absence of α-BoNT/Aneutralizing antibodies; b) treating a cell from an established cellline with the test sample, wherein the cell from an established cellline is susceptible to BoNT/A intoxication; c) isolating from thetreated cells a SNAP-25 component comprising a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond; d) fixing the SNAP-25 component to a solid phase support;e) contacting the SNAP-25 component with an α-SNAP-25 antibody, whereinthe α-SNAP-25 antibody binds an eptiope comprising a carboxyl-terminusat the P₁ residue of the BoNT/A cleavage site scissile bond from aSNAP-25 cleavage product; f) detecting the presence of anantibody-antigen complex comprising the α-SNAP-25 antibody and theSNAP-25 cleavage product; g) repeating steps b-f with a negative controlsample instead of a test sample, the negative control sample comprisinga BoNT/A and a serum known not to contain α-BoNT/A neutralizingantibodies; and h) comparing the amount of antibody-antigen complexdetected in step f to the amount of antibody-antigen complex detected instep g, wherein detection of a lower amount of antibody-antigen complexdetected in step f relative to the amount of antibody-antigen complexdetected in step g is indicative of the presence of α-BoNT/Aneutralizing antibodies.

26. A method of determining BoNT/A immunoresistance in a mammalcomprising the steps of: a) adding a BoNT/A to a test sample obtainedfrom a mammal being tested for the presence or absence of α-BoNT/Aneutralizing antibodies; b) treating a cell from an established cellline with the test sample, wherein the cell from an established cellline can uptake BoNT/A; c) isolating from the treated cells a SNAP-25component comprising a SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond; d) contacting the SNAP-25 component with an α-SNAP-25 antibody,wherein the α-SNAP-25 antibody binds an eptiope comprising acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond from a SNAP-25 cleavage product; e) detecting the presence of anantibody-antigen complex comprising the α-SNAP-25 antibody and theSNAP-25 cleavage product; f) repeating steps b-e with a negative controlsample instead of a test sample, the negative control sample comprisinga BoNT/A and a serum known not to contain α-BoNT/A neutralizingantibodies; and g) comparing the amount of antibody-antigen complexdetected in step e to the amount of antibody-antigen complex detected instep f, wherein detection of a lower amount of antibody-antigen complexdetected in step e relative to the amount of antibody-antigen complexdetected in step f is indicative of the presence of α-BoNT/Aneutralizing antibodies.

27. A method of determining BoNT/A immunoresistance in a mammalcomprising the steps of: a) adding a BoNT/A to a test sample obtainedfrom a mammal being tested for the presence or absence of α-BoNT/Aneutralizing antibodies; b) treating a cell from an established cellline with the test sample, wherein the cell from an established cellline can uptake BoNT/A; c) isolating from the treated cells a SNAP-25component comprising a SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond; d) contacting the SNAP-25 component with an α-SNAP-25 antibodylinked to a solid phase support, wherein the α-SNAP-25 antibody binds aneptiope comprising a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product; e)detecting the presence of an antibody-antigen complex comprising theα-SNAP-25 antibody and the SNAP-25 cleavage product; f) repeating stepsb-e with a negative control sample instead of a test sample, thenegative control sample comprising a BoNT/A and a serum known not tocontain α-BoNT/A neutralizing antibodies; and g) comparing the amount ofantibody-antigen complex detected in step e to the amount ofantibody-antigen complex detected in step f, wherein detection of alower amount of antibody-antigen complex detected in step e relative tothe amount of antibody-antigen complex detected in step f is indicativeof the presence of α-BoNT/A neutralizing antibodies.

28. A method of determining BoNT/A immunoresistance in a mammalcomprising the steps of: a) adding a BoNT/A to a test sample obtainedfrom a mammal being tested for the presence or absence of α-BoNT/Aneutralizing antibodies; b) treating a cell from an established cellline with the test sample, wherein the cell from an established cellline can uptake BoNT/A; c) isolating from the treated cells a SNAP-25component comprising a SNAP-25 cleavage product having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond; d) fixing the SNAP-25 component to a solid phase support; e)contacting the SNAP-25 component with an α-SNAP-25 antibody, wherein theα-SNAP-25 antibody binds an eptiope comprising a carboxyl-terminus atthe P₁ residue of the BoNT/A cleavage site scissile bond from a SNAP-25cleavage product; f) detecting the presence of an antibody-antigencomplex comprising the α-SNAP-25 antibody and the SNAP-25 cleavageproduct; g) repeating steps b-f with a negative control sample insteadof a test sample, the negative control sample comprising a BoNT/A and aserum known not to contain α-BoNT/A neutralizing antibodies; and h)comparing the amount of antibody-antigen complex detected in step f tothe amount of antibody-antigen complex detected in step g, whereindetection of a lower amount of antibody-antigen complex detected in stepf relative to the amount of antibody-antigen complex detected in step gis indicative of the presence of α-BoNT/A neutralizing antibodies.

29. The method of 17-22 and 23-25, wherein the cell is susceptible toBoNT/A intoxication by about 500 pM or less, by about 400 pM or less, byabout 300 pM or less, by about 200 pM or less, by about 100 pM or lessof a BoNT/A.

30. The method of 20-22 and 26-28, wherein the cell can uptake about 500pM or less, by about 400 pM or less, by about 300 pM or less, by about200 pM or less, by about 100 pM or less of BoNT/A.

31. The method of 17-22, wherein the sample comprises about 100 ng orless, about 10 ng or less, about 1 ng or less, 100 fg or less, 10 fg orless, or 1 fg or less of a BoNT/A

32. The method of 17-22, wherein the sample comprises about 100 nM orless, about 10 nM or less, about 1 nM or less, about 100 pM or less,about 10 pM or less, about 1 pM or less, about 100 fM or less, about 10fM or less, or about 1 fM or less of a BoNT/A.

33. The method of 17-28, wherein the α-SNAP-25 antibody is the isolatedα-SNAP-25 antibody of 5-16.

34. The method of 17-28, wherein the presence of an antibody-antigencomplex is detected by an immuno-blot analysis, an immunoprecipitationanalysis, an ELISA, or a sandwich ELISA

35. The method of 17-28, wherein the immuno-based method has asignal-to-noise ratio for the lower asymptote of at least 3:1, at least5:1, at least 10:1, at least 20:1, at least 50:1, or at least 100:1.

36. The method of 17-28, wherein the immuno-based method has asignal-to-noise ratio for the higher asymptote of at least 10:1, atleast 20:1, at least 50:1, at least 100:1, at least 200:1, at least300:1, at least 400:1, at least 500:1, or at least 600:1.

37. The method of 17-28, wherein the immuno-based method can detect theEC₅₀ activity of, e.g., at least 100 ng, at least 50 ng, at least 10 ng,at least 5 ng, at least 100 pg, at least 50 pg, at least 10 pg, at least5 pg, at least 100 fg, at least 50 fg, at least 10 fg, or at least 5 fg.

38. The method of 17-28, wherein the immuno-based method can detect theEC₅₀ activity of, e.g., at least 10 nM, at least 5 nM, at least 100 pM,at least 50 pM, at least 10 pM, at least 5 pM, at least 100 fM, at least50 fM, at least 10 fM, at least 5 fM, or at least 1 fM.

39. The method of 17-28, wherein the immuno-based method has an LOD of,e.g., 10 pg or less, 9 pg or less, 8 pg or less, 7 pg or less, 6 pg orless, 5 pg or less, 4 pg or less, 3 pg or less, 2 pg or less, 1 pg orless of a BoNT/A

40. The method of 17-28, wherein the immuno-based method has an LOD of,e.g., 100 fM or less, 90 fM or less, 80 fM or less, 70 fM or less, 60 fMor less, 50 fM or less, 40 fM or less, 30 fM or less, 20 fM or less, or10 fM or less of a BoNT/A.

41. The method of 17-28, wherein the immuno-based method has an LOQ of,e.g., 10 pg or less, 9 pg or less, 8 pg or less, 7 pg or less, 6 pg orless, 5 pg or less, 4 pg or less, 3 pg or less, 2 pg or less, 1 pg orless of a BoNT/A

42. The method of 17-28, wherein the immuno-based method has an LOQ of,e.g., 100 fM or less, 90 fM or less, 80 fM or less, 70 fM or less, 60 fMor less, 50 fM or less, 40 fM or less, 30 fM or less, 20 fM or less, or10 fM or less of a BoNT/A.

43. The method of 17-28, wherein the immuno-based method can distinguisha fully-active BoNT/A from a partially-active BoNT/A having 70% or less,60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10%or less the activity of a fully-active BoNT/A.

EXAMPLES Example I Screening of Candidate Cell Lines

The following example illustrates how to identify established cell linessusceptible to BoNT/A intoxication or have BoNT/A uptake capacityrequired for a method of detecting BoNT/A activity disclosed in therpesent specification.

1. Growth of Stock Culture of Candidate Cell Lines.

To grow the cell lines, a suitable density of cells from the cell linebeing tested were plated in a 162 cm² tissue culture flask containing 30mL of a suitable growth medium (see Table 1), and grown in a 37° C.incubator under 5% or 10% carbon dioxide until cells reached the desireddensity.

TABLE 1 Media Used in Cell Line Screening. Cell Line Serum Growth MediaComposition Kelly RPMI 1640, 10% fetal bovine serum, 1% Penicillin- SiMaStreptomycin, 2 mM L-Glutamine NB69 RPMI 1640, 15% fetal bovine serum,1% Penicillin- Streptomycin CHP-126 RPMI 1640, 20% fetal bovine serum,1% Pencillin- Streptomycin N4TG3 RPMI 1640, 10% fetal bovine serum, 1%Pencillin- Streptomycin, 100 μM 6-thioguanine MHH-NB-11 RPMI 1640, 10%fetal bovine serum, 1% Pencillin- Streptomycin, 2 mM L-glutamine, 0.1 mMnon- essential amino acids PC12 RPMI 1640, 5% heat-inactivated fetalbovine serum, 10% equine serum, 2 mM GlutaMAX ™, 10 mM HEPES, 1 mMsodium pyruvate, 1% Penicillin- Streptomycin N18TG2 DMEM (11885-084,Gibco), 10% fetal bovine serum, 1% Penicillin-Streptomycin, 100 μM6-thioguanine N1E-115 90% DMEM, 10% heat-inactivated fetal bovine serum,N18 2 mM Glutamine, 2 mM glucose ND8/34 NG108-15 NG115-401L NS20YSK-N-SH SK-N-DZ 90% DMEM, 10% heat-inactivated fetal bovine serum,SK-N-F1 4 mM glucose, 0.1 mM non-essential amino acids, 1.5 g/L NaHCO₃BE(2)-C EMEM(11090-081, Gibco), Ham's F12 (11765-054, BE(2)-M17 Gibco),10% heat-inactivated fetal bovine serum, 2 mM CHP-212 Glutamine, 0.1 mMnon-essential amino acids, LA-1-55n LA-N-1 MC-1XC SK-N-BE(2) SH-SY5Y NB41A3 Ham's F10 (12471-017, Gibco), 2.5% heat-inactivated fetal bovineserum, 15% heat-inactivated horse serum, 2 mM Glutamine Neuro-2a EMEM,10% heat-inactivated fetal bovine serum, 2 mM Glutamine, 0.1 mMnon-essential amino acids, 1.5 g/L NaHCO₃, 1 mM Sodium pyruvate

2. Single-Dose Screening of Candidate Cell Lines Using 1 nM BoNT/A.

One parameter tested to improve the sensitivity of a cell-based assaywas to identify suitable cell lines that exhibited a good capacity touptake a Clostridial neurotoxin and adhere to a substrate surface.Initially, cell lines were tested for their ability to uptake 1 nMBoNT/A and their ability to attach to a surface. To determine whether acell line was able to uptake 1 nM BoNT/A, a suitable density of cellsfrom a stock culture of the cell line being tested was plated into thewells of 24-well tissue culture plates containing 1 mL of an appropriateserum growth medium (Table 1). The cells were grown in a 37° C.incubator under 5% carbon dioxide until cells reached the desireddensity (approximately 18 to 24 hours). The growth media was aspiratedfrom each well and replaced with either 1) fresh growth media containingno toxin (untreated cell line) or 2) fresh growth media containing 1 nMof a BoNT/A complex (treated cell line). After an overnight incubation,the cells were washed by aspirating the growth media and rinsing eachwell with 200 μl of 1×PBS. To harvest the cells, the 1×PBS wasaspirated, the cells were lysed by adding 50 μl of 2×SDS Loading Buffer,the lysate was transferred to a clean test tube and the sample washeated to 95° C. for 5 minutes.

To detect for the presence of both uncleaved SNAP-25 substrate andcleaved SNAP-25 products, an aliquot from each harvested sample wasanalyzed by Western blot. In this analysis, a 12 μl aliquot of theharvested sample was separated by MOPS polyacrylamide gelelectrophoresis using NuPAGE® Novex 12% Bis-Tris precast polyacrylamidegels (Invitrogen Inc., Carlsbad, Calif.) under denaturing, reducingconditions. Separated peptides were transferred from the gel ontopolyvinylidene fluoride (PVDF) membranes (Invitrogen Inc., Carlsbad,Calif.) by Western blotting using a Trans-Blot® SD semi-dryelectrophoretic transfer cell apparatus (Bio-Rad Laboratories, Hercules,Calif.). PVDF membranes were blocked by incubating at room temperaturefor 2 hours in a solution containing Tris-Buffered Saline (TBS) (25 mM2-amino-2-hydroxymethyl-1,3-propanediol hydrochloric acid (Tris-HCl)(pH7.4), 137 mM sodium chloride, 2.7 mM potassium chloride), 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate), 2% Bovine Serum Albumin(BSA), 5% nonfat dry milk. Blocked membranes were incubated at 4° C. forovernight in TBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate), 2% BSA, and 5% nonfat dry milk containing either 1) a1:5,000 dilution of an α-SNAP-25 mouse monoclonal antibody as theprimary antibody (SMI-81; Sternberger Monoclonals Inc., Lutherville,Md.); or 2) a 1:5,000 dilution of S9684 α-SNAP-25 rabbit polyclonalantiserum as the primary antibody (Sigma, St. Louis, Mo.). Bothα-SNAP-25 mouse monoclonal and rabbit polyclonal antibodies can detectboth the uncleaved SNAP-25 substrate and the SNAP-25 cleavage product,allowing for the assessment of overall SNAP-25 expression in each cellline and the percent of SNAP-25 cleaved after BoNT/A treatment as aparameter to assess the amount of BoNT/A uptake. Primary antibody probedblots were washed three times for 15 minutes each time in TBS, TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). Washed membranes wereincubated at room temperature for 2 hours in TBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate), 2% BSA, and 5% nonfat drymilk containing either 1) a 1:10,000 dilution of goat polyclonalanti-mouse immunoglobulin G, heavy and light chains (IgG, H+L) antibodyconjugated to horseradish peroxidase (Zymed, South San Francisco,Calif.) as a secondary antibody; or 2) a 1:10,000 dilution of goatpolyclonal anti-rabbit immunoglobulin G, heavy and light chains (IgG,H+L) antibody conjugated to horseradish peroxidase (Zymed, South SanFrancisco, Calif.) as a secondary antibody. Secondary antibody-probedblots were washed three times for 15 minutes each time in TBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). Signal detectionof the labeled SNAP-25 products were visualized using the ECL Plus™Western Blot Detection System (GE Healthcare, Amersham Biosciences,Piscataway, N.J.) and the membrane was imaged and the percent of cleavedquantified with a Typhoon 9410 Variable Mode Imager and Imager Analysissoftware (GE Healthcare, Amersham Biosciences, Piscataway, N.J.). Thechoice of pixel size (100 to 200 pixels) and PMT voltage settings (350to 600, normally 400) depended on the individual blot. Table 2 indicatesthe cell lines where a SNAP-25 cleavage product was detected whentreated with 1 nM BoNT/A. The following cell lines exhibited both anuptake of 1 nM BoNT/A and appropriate attachment to a substrate surface:BE(2)-M17, IMR-32, Kelly, LA1-55n, N1E-115, N4TG3, N18, Neuro-2a,NG108-15, PC12, SH-SYSY, SiMa and SK-N-BE(2)-C.

To determine whether a cell line was able to attach to a surface, asuitable density of cells from a stock culture of the cell line beingtested was plated into the wells of 24-well tissue culture platescontaining 1 mL of an appropriate growth media (Table 1). The cells weregrown in a 37° C. incubator under 5% carbon dioxide until cells reachthe desired density (approximately 18 to 24 hours). Cell attachment wasassessed by the percentage of cells that adhered to the bottom wellsurface of the tissue plate relative to the total number of cellsseeded. Cell lines CHP-126, IMR-32, LA-N-1, MC-IXC, NG115-401L,SK-N-BE(2)-C, SK-N-F1 and SK-N-MC were deemed unsuitable because eachcell line exhibited less than 50% attachment (Table 2). All other cellslines tested exhibited suitable cell attachment characteristics (Table2).

TABLE 2 Single-Dose Screening of Candidate Cell Lines Using 1 nM BoNT/A.1 nM BoNT/A Cell Line Description Source Uptake Attachment BE(2)-C Humanneuroblastoma ATCC CRL-2268 No >60% BE(2)-M17 Human neuroblastoma ATCCCRL-2267 Yes >60% CHP-126 Human neuroblastoma DSMZ ACC 304 No <50%CHP-212 Human neuroblastoma ATCC CRL-2273 No >60% HCN-1a Brain corticalneuron ATCC CRL-10442 No >60% HCN-2 Brain cortical neuron ATCC CRL-10742No >60% IMR-32 Human neuroblastoma ATCC CRL-127 Yes <50% Kelly Humanneuroblastoma ECACC 92110411 Yes >60% Kelly Human neuroblastoma DSMZ ACC355 Yes >60% LA1-55n Human neuroblastoma ECACC 06041203 Yes >60% LA-N-1Human neuroblastoma ECACC 06041201 — <25% MC-IXC Human neuroepitheliomaATCC CRL-2270 — <25% MHH-NB-11 Human neuroblastoma DSMZ ACC 157 No >60%N1E-115 Mouse neuroblastoma ATCC CCL-2263 Yes >60% N4TG3 Mouseneuroblastoma DSMZ ACC 101 No >60% N18TG2 Mouse neuroblastoma DSMZ ACC103 No >60% NB4 1A3 Mouse neuroblastoma ECACC 89121405 No >60% ND3 Mouseneuroblastoma/primary ECACC 92090901 No >60% neonatal rat DRG hybridND7/23 Mouse neuroblastoma/primary rat ECACC 92090903 No >60% DRG hybridND8 Mouse neuroblastoma/primary ATCC No >60% neonatal rat DRG hybridND8/34 Mouse neuroblastoma ECACC 92090904 No >60% ND15 Mouseneuroblastoma/primary ECACC 92090907 No >60% neonatal rat DRG hybridND27 Mouse neuroblastoma/primary rat ECACC 92090912 No >60% DRG hybridNB69 Human neuroblastoma ECACC 99072802 No >60% NDC Mouseneuroblastoma/primary ECACC 92090913 No >60% neonatal rat DRG hybridNeuro-2a Mouse neuroblastoma ATCC CCL-131 Yes >60% NG108-15 Mouseneuroblastoma/rat glioma ECACC 88112302 Yes >60% hybrid NG115-401L Mouseneuroblastoma/rat glioma ECACC 87032003 No <50% hybrid NS20Y Mouseneuroblastoma DSMZ ACC 94 No >60% PC12 Rat pheochromocytoma ATCCCRL-1721 Yes >60% SH-SY5Y Human neuroblastoma ATCC CRL-2266 Yes >60%SiMa Human neuroblastoma DSMZ ACC 164 Yes >60% SK-N-BE(2)- Humanneuroblastoma ATCC CRL-2271 Yes <50% C SK-N-AS Human neuroblastoma ATCCCRL-2137 No >60% SK-N-DZ Human neuroblastoma ATCC CRL-2149 No >60%SK-N-F1 Human neuroblastoma ATCC CRL-2142 No <50% SK-N-MC Humanneuroblastoma ATCC HTB-10 — <25% SK-N-SH Human neuroblastoma ECACC86012802 No >60% TE 189.T Spinal cord ATCC CRL-7947 No >60%

Example II Evaluation of Growth Conditions on Neurotoxin Uptake inCandidate Cell Lines

The following example illustrates how to determine growth conditions forestablished cell lines that maximize susceptible to BoNT/A intoxicationor have BoNT/A uptake capacity.

1. Effects of Cell Differentiation on Neurotoxin Uptake of CandidateCell Lines.

To determine whether cell differentiation improved neurotoxin uptake,cell lines exhibiting uptake of 1 nM BoNT/A were transferred intoserum-free medium to induced differentiation. A suitable density ofcells from a stock culture of the cell line being tested was plated intothe wells of 24-well tissue culture plates containing 1 mL of aserum-free medium containing Minimum Essential Medium with 2 mMGlutaMAX™ I with Earle's salts, 0.1 mM Non-Essential Amino Acids, 10 mMHEPES, 1 mM Sodium Pyruvate, 100 units/mL Penicillin, and 100 μg/mLStreptomycin. These cells were incubated in a 37° C. incubator under 5%carbon dioxide until the cells differentiated, as assessed by standardand routine morphological criteria, such as growth arrest and neuriteextension (approximately 2 to 3 days). As a control, a suitable densityof cells from a stock culture of the cell line being tested was platedinto the wells of 24-well tissue culture plates containing 1 mL of anappropriate growth medium (Table 1). These undifferentiated controlcells were grown in a 37° C. incubator under 5% carbon dioxide untilcells reach the desired density (approximately 18 to 24 hours). Themedia from both differentiated and undifferentiated control cultures wasaspirated from each well and replaced with fresh media containing either0 (untreated sample), 0.1 nM, 0.3 nM, or 1 nM of a BoNT/A complex. Afteran overnight incubation, the cells were washed and harvested asdescribed in Example I.

To detect for the presence of cleaved SNAP-25 products, an aliquot fromeach harvested sample was analyzed by Western blot as described inExample I, except that harvested samples are separated by SDS-PAGE using12% 26-well Criterion gels (Bio-Rad Laboratories, Hercules, Calif.), andthe rabbit polyclonal α-SNAP-25₁₉₇ antibody serum was used as theprimary antibody (see Example IV). Table 3 indicates the cell lines thatexhibited a SNAP-25 cleavage product when treated with 0.1 nM BoNT/A. Ofthe cell lines tested, only the SiMa and Neuro-2a cell lines exhibitedan uptake of 0.1 nM BoNT/A in the undifferentiated state. However,besides SiMa and Neuro-2a, the cell lines N18, LA1-55n, PC12, andSH-SY5Y all exhibited an uptake of 0.1 nM BoNT/A in the differentiatedstate.

TABLE 3 Effects of Cell Differentiation on Neurotoxin Uptake ofCandidate Cell Lines. 0.1 nM BoNT/A Uptake Cell Line Description SourceUndifferentiated Differentiated BE(2)-M17 Human neuroblastoma ATCCCRL-2267 No No Kelly Human neuroblastoma DSMZ ACC 355 No No LA1-55nHuman neuroblastoma ECACC 06041203 No Yes N1E-115 Mouse neuroblastomaATCC CCL-2263 No Not Tested N4TG3 Mouse neuroblastoma DSMZ ACC 101 NoNot Tested N18 Mouse neuroblastoma/rat ECACC 88112301 No Yes gliomahybrid Neuro-2a Mouse neuroblastoma ATCC CCL-131 Yes Yes NG108-15 Mouseneuroblastoma/rat ECACC 88112302 No Not Tested glioma hybrid PC12 Ratpheochromocytoma ATCC CRL-1721 No Yes SH-SY5Y Human neuroblastoma ATCCCRL-2266 No Yes SiMa Human neuroblastoma DSMZ ACC 164 Yes Yes SK-N-Human neuroblastoma ATCC CRL-2271 No Not Tested BE(2)-C

2. Effects of Ganglioside Treatment on Neurotoxin Uptake ofDifferentiated Candidate Cell Lines.

To determine whether treatments improving low-affinity binding ofneurotoxin could improve neurotoxin uptake, differentiated cell linesexhibiting uptake of 1 nM BoNT/A were treated with ganglioside GT1b. Asuitable density of cells from a stock culture of the cell line beingtested was plated into the wells of 24-well tissue culture platescontaining serum-free medium as described above, with or without 25μg/mL GT1b (Alexis Biochemicals, San Diego, Calif.). These cells wereincubated in a 37° C. incubator under 5% carbon dioxide until the cellsdifferentiated, as assessed by standard and routine morphologicalcriteria as described above. The media was aspirated from each well andreplaced with fresh serum-free media containing either 0 (untreatedsample), 1.9 pM, 3.7 pM, 7.4 pM, 14.8 pM, 29.7 pM, 59.4 pM, 118.8 pM,237.5 pM, 574 pM, 950 pM, and 1900 pM of a BoNT/A complex. The celllines were incubated at two different times, 24 hours and 48 hours.After toxin incubation, the cells were washed and harvested as describedin Example I.

To detect for the presence of cleaved SNAP-25 products, an aliquot fromeach harvested sample was analyzed by Western blot as described inExample I, except that harvested samples are separated by SDS-PAGE using12% 26-well Criterion gels (Bio-Rad Laboratories, Hercules, Calif.), andthe rabbit polyclonal α-SNAP-25₁₉₇ antibody serum was used as theprimary antibody (see Example IV). Table 4 indicates the effects ofgangliosides treatment on the ability of differentiated cell lines touptake BoNT/A. These results indicate the lowest concentration of BoNT/Athat will produce a detectable band of SNAP-25 cleavage product in theWestern blot.

TABLE 4 Effects of Ganglioside Treatment on Neurotoxin Uptake ofCandidate Cell Lines. BoNT/A Uptake 24 Hour 48 Hour Cell LineDescription Source Incubation Incubation BE(2)-M17 Human neuroblastomaATCC CRL-2267 237.5 pM 118.8 pM Kelly Human neuroblastoma DSMZ ACC 355Not Tested Not Tested LA1-55n Human neuroblastoma ECACC   15 pM  7.4 pM06041203 N1E-115 Mouse neuroblastoma ATCC CCL-2263 Not Tested Not TestedN4TG3 Mouse neuroblastoma DSMZ ACC 101 Not Tested Not Tested N18 Mouseneuroblastoma/rat ECACC  14.8 pM  7.4 pM glioma hybrid 88112301 Neuro-2aMouse neuroblastoma ATCC CCL-131  7.4 pM  7.4 pM NG108-15 Mouseneuroblastoma/rat ECACC Not Tested Not Tested glioma hybrid 88112302PC12 Rat pheochromocytoma ATCC CRL-1721  7.4 pM  7.4 pM SH-SY5Y Humanneuroblastoma ATCC CRL-2266 Not Tested Not Tested SiMa Humanneuroblastoma DSMZ ACC 164  1.9 pM  1.9 pM SK-N-BE(2)- Humanneuroblastoma ATCC CRL-2271 Not Tested Not Tested C3. Development of Serum-Free Media with Cell Differentiating Propertiesthat Enhanced Neurotoxin Uptake of Candidate Cell Lines.

To determine whether treatment improvements that induce celldifferentiation could improve neurotoxin uptake, SiMa, Neuro-2a and PC12cell lines were grown in various serum-free medium to induceddifferentiation. A suitable density of cells from a stock culture of thecell line being tested was plated into the wells of 24-well tissueculture plates containing 1 mL of various test serum-free medium.Parameters tested were 1) the effect of different basal media on BoNT/Auptake (MEM and RPMI 1649); 2) the effect of the presence or absence ofneurotrophic factors on BoNT/A uptake (N2 supplement and B27supplement); 3) the effect of the presence or absence of differentiationfactors on BoNT/A uptake (retinoic acid and nerve growth factor); and 4)the effect of the presence or absence of serum on BoNT/A uptake(serum-free media and reduced serum media). As a control, a suitabledensity of cells from a stock culture of the cell line being tested wasplated into the wells of 24-well tissue culture plates containing 1 mLof a control serum-free media (Minimum Essential Medium, 2 mM GlutaMAX™I with Earle's salts, 0.1 mM Non-Essential Amino Acids, 10 mM HEPES, 1mM Sodium Pyruvate, 100 units/mL Penicillin, and 100 μg/mLStreptomycin). These cells were incubated in a 37° C. incubator under 5%carbon dioxide until the cells differentiated, as assessed by standardand routine morphological criteria, such as growth arrest and neuriteextension (approximately 2 to 3 days). The media was aspirated from eachwell and replaced with fresh serum-free media containing either 0(untreated sample), 0.005 pM, 0.015 pM, 0.05 pM, 0.14 pM, 0.42 pM, 1.2pM, 3.7 pM, 11 pM, 33 pM, 100 pM and 300 pM of a BoNT/A complex. Inaddition, the differentiated cells were treated with BoNT/A for 24 hrsfollowed by a media change and 48 hrs incubation in fresh media withouttoxin to allow for the accumulation of SNAP-25 cleavage product. Thecells were then washed and harvested as described in Example I.

TABLE 5 Serum Free Media Used for Differentiating Cell Lines. Cell LineTest Serum Free Media Composition LA1-55n Minimum Essential Medium with2 mM GlutaMAX ™ I with Earle's salts, 0.1 mM Non-Essential Amino- Acids,10 mM HEPES, 1 × N2 supplement, and 1 × B27 supplement Neuro-2a MinimumEssential Medium, 2 mM GlutaMAX ™ I with Earle's salts, 1 × B27supplement, 1 × N2 supplement, 0.1 mM Non-Essential Amino Acids, 10 mMHEPES PC12 RPMI 1640, 2 mM GlutaMAX ™, 1 × B27 supplement, 1 × N2supplement, 10 mM HEPES, 1 mM sodium pyruvate, 1%Penicillin-Streptomycin and 50 ng/mL Nerve Growth Factor SiMa MinimumEssential Medium, 2 mM GlutaMAX ™ I with Earle's salts, 1 × B27supplement, 1 × N2 supplement, 0.1 mM Non-Essential Amino Acids, 10 mMHEPES

To detect for the presence of a SNAP-25 cleavage product, an aliquotfrom each harvested sample was analyzed by Western blot as described inExample I, except that harvested samples are separated by SDS-PAGE using12% 26-well Criterion gels (Bio-Rad Laboratories, Hercules, Calif.), andan α-SNAP-25 rabbit polyclonal antibody serum was used (see Example IV).The most optimized media determined for each cell line is shown in Table5. Table 6 indicates the lowest amount of a SNAP-25 cleavage productdetected when the cell lines were grown in this optimized serum-freemedium. Use of the optimized serum-free medium resulted in the detectionof BoNT/A activity signals with acceptable signal-to-noise ratios inLA1-55n, Neuro-2a, PC-12, and SiMa cell lines (FIG. 2). For example,optimized differentiation conditions resulted in a 5-fold increase inSNAP-25 cleavage product detection as compared to the control serum-freemedia for Neuro-2a and PC12 cells, and almost 50-fold for SiMa cells. Inaddition, a minimal signal to noise ratio of 3:1 for the lower asymptoteand 10:1 for the upper asymptote is required to develop a robust assayamenable for validation. Wth the exception of LA-1-55n, all optimizedcell lines provided a signal to noise ratio for the lower asymptote ofat least 3:1 when the signal detected from the 1.2 pM dose was comparedto the background signal of 0 pM BoNT/A (FIG. 2). In addition, alloptimized cell lines provided a signal to noise ratio for the upperasymptote of at least 100:1 when the signal from the 300 pM dose wascompared to the background signal of 0 pM BoNT/A (FIG. 2). These resultsindicate that any of these cell lines could be used to develop animmuno-based method for detecting BoNT/A activity as disclosed in thepresent specification because the assay was detecting the presence of pMamounts of BoNT/A.

TABLE 6 Effects of Optimized Serum-Free Media on Neurotoxin Uptake ofCandidate Cell Lines. BoNT/A Uptake Control Optimized Serum-FreeSerum-Free Cell Line Description Source Media Media BE(2)-M17 Humanneuroblastoma ATCC CRL-2267 Not Tested Not Tested Kelly Humanneuroblastoma DSMZ ACC 355 Not Tested Not Tested LA1-55n Humanneuroblastoma ECACC 06041203  7.4 pM  3.7 pM N1E-115 Mouse neuroblastomaATCC CCL-2263 Not Tested Not Tested N4TG3 Mouse neuroblastoma DSMZ ACC101 Not Tested Not Tested N18 Mouse neuroblastoma/rat ECACC 88112301 NotTested Not Tested glioma hybrid Neuro-2a Mouse neuroblastoma ATCCCCL-131  3.7 pM  0.8 pM NG108-15 Mouse neuroblastoma/rat ECACC 88112302Not Tested Not Tested glioma hybrid PC12 Rat pheochromocytoma ATCCCRL-1721  2.0 pM  0.42 pM SH-SY5Y Human neuroblastoma ATCC CRL-2266 NotTested Not Tested SiMa Human neuroblastoma DSMZ ACC 164 0.23 pM 0.005 pMSK-N-BE(2)- Human neuroblastoma ATCC CRL-2271 Not Tested Not Tested C

Example III Development of α-SNAP-25 Monoclonal Antibodies thatSelectively Bind a SNAP-25 Epitope Having a Free Carboxyl-Terminus atthe P₁ Residue of the BoNT/a Cleavage Site Scissile Bond

The following example illustrates how to make α-SNAP-25 monoclonalantibodies that can selectively bind to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond.

1. Generation of α-SNAP-25 Monoclonal Antibodies.

To develop monoclonal α-SNAP-25 antibodies that bind an epitopecomprising a carboxyl-terminus at the P₁ residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product, the13-residue peptide CDSNKTRIDEANQ_(COOH) (SEQ ID NO: 38) was designed asa SNAP-25 cleavage product antigen. This peptide comprises a flexiblelinker region and a N-terminal Cysteine residue for conjugation to KLHand amino acids 186-197 of human SNAP-25 (SEQ ID NO: 5) with acarboxylated C-terminal glutamine (SEQ ID NO: 38). The generation ofmonoclonal antibodies to well-chosen, unique peptide sequences providescontrol over epitope specificity, allowing the identification of aparticular subpopulation of protein among a pool of closely relatedisoforms. Blast searches revealed that this peptide has high homologyonly to SNAP-25 and almost no possible cross-reactivity with otherproteins in neuronal cells. The sequence was also carefully scrutinizedby utilizing computer algorithms to determine hydropathy index, proteinsurface probability, regions of flexibility, and favorable secondarystructure, followed by proper orientation and presentation of the chosenpeptide sequence. The peptide was synthesized and conjugated to KeyholeLimpet Hemocyanin (KLH) to increase immunogenicity. Six Balb/c mice wereimmunized with this peptide, and after three immunizations in abouteight weeks, the mice were bled for testing. The blood was allowed toclot by incubating at 4° C. for 60 minutes. The clotted blood wascentrifuged at 10,000×g at 4° C. for 10 minutes to pellet the cellulardebris. The resulting serum sample was dispensed into 50 μl aliquots andstored at −20° C. until needed.

A similar strategy based on other SNAP-25 antigens disclosed in thepresent specification is used to develop α-SNAP-25 monoclonal antibodiesthat bind an epitope comprising a carboxyl-terminus at the P₁ residuefrom the BoNT/A cleavage site scissile bond from a SNAP-25 cleavageproduct. For example, the SNAP-25 antigen of SEQ ID NO: 45 can beconjugated to KLH instead of the SNAP-25 antigen of SEQ ID NO: 38. Asanother example, the amino acids 186-197 of human SNAP-25 from theSNAP-25 antigen of SEQ ID NO: 38 can be replaced with SEQ ID NO: 32, SEQID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 39,SEQ ID NO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, or SEQ IDNO: 44.

2. Screening for the Presence of α-SNAP-25 Monoclonal Antibodies.

To determine the presence of an α-SNAP-25 monoclonal antibody that canselectively bind to a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond, comparative ELISAand cell-based cleavage assay were performed using the extracted mouseserum. For comparative ELISA, two fusion proteins were constructed:BirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ of SEQ ID NO: 48 and theBirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ of SEQ ID NO: 49.BirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ comprised a naturally-biotinylated 16 aminoacid BirA peptide of SEQ ID NO: 50 amino-terminally linked to a SNAP-25peptide comprising amino acids 134-197 of SEQ ID NO: 5.BirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ comprised a naturally-biotinylated 16 aminoacid BirA peptide of SEQ ID NO: 50 amino-terminally linked to a SNAP-25peptide comprising amino acids 134-206 of SEQ ID NO: 5. These twosubstrates were suspended in 1×PBS at a concentration of 10 μg/mLBirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ and the BirA-HisTag®-SNAP-25₁₃₄₋₂₉₆. TheBirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ and the BirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ werecoated onto separate plates by adding approximately 100 μl of theappropriate Substrate Solution and incubating the plates at roomtemperature for one hour. Washed plates were incubated at 37° C. for onehour in 0.5% BSA in 1×TBS containing a 1:10 to 1:100 dilution of anantibody-containing serum derived from one of the six immunized mice(Mouse 1, Mouse 2, Mouse 3, Mouse 4, Mouse 5, and Mouse 6). Primaryantibody probed plates were washed four times for 5 minutes each time in200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate).Washed plates were incubated at 37° C. for 1 hour in 1×TBS containing a1:10,000 dilution of goat polyclonal anti-mouse IgG antibody conjugatedto Horseradish peroxidase (Pierce Biotechnology, Rockford, Ill.) as asecondary antibody. Secondary antibody-probed plates were washed fourtimes in 200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate). Chromogenic detection of the labeled SNAP-25 productswere visualized by chromogenic detection using ImmunoPure TMB substratekit (Pierce Biotechnology, Rockford, Ill.). The development of a yellowcolor in the BirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ coated plates, but not theBirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ coated plates, indicated that the α-SNAP-25antibody preferentially recognized the SNAP-25₁₉₇ cleavage product. Theresulted indicated that of the six mice used for immunization, threemice (Mouse 2, Mouse 3, and Mouse 4) had higher titers and morespecificity towards a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond.

These results were confirmed using an ELISA light chain activity assay.A 96-well Reacti-Bind Streptavidin coated plates (Pierce Biotechnology,Rockford, Ill.) were prepared by adding approximately 100 μl of thefollowing Substrate Solution: Rows A-C were coated with 100 μL ofBirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ at twelve different concentrations; Rows D-Hwere coated with 100 μL of BirA-HisTag®-SNAP-25₁₃₄₋₂₉₆ at 10 μg/mL. Theplates were washed by aspirating the Substrate Solution and rinsing eachwell three times with 200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20)sorbitan monolaureate). Dilutions of BoNT/A were pre-reduced at 37° C.for 20 minutes in BoNT/A Incubation Buffer (50 mM HEPES, pH 7.4, 1%fetal bovine serum, 10 pM ZnCl₂, 10 mM dithiothrietol) and 100 μl of thepre-reduced BoNT/A was added to the substrate-coated plates andincubated at 37° C. for 90 minutes. BoNT/A treated plates were washed byaspirating the BoNT/A Incubation Buffer and rinsing each plate threetimes with 200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate). Washed plates were incubated at 37° C. for one hour in0.5% BSA in 1×TBS containing a 1:10 to 1:100 dilution of theantibody-containing serum being tested. Primary antibody probed plateswere washed four times for 5 minutes each time in 200 μl TBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). Washed plateswere incubated at 37° C. for 1 hour in 1×TBS containing a 1:10,000dilution of goat polyclonal anti-mouse IgG antibody conjugated toHorseradish peroxidase (Pierce Biotechnology, Rockford, Ill.) as asecondary antibody. Secondary antibody-probed plates were washed fourtimes in 200 μl TBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate). Chromogenic detection of the labeled SNAP-25 productswere visualized by chromogenic detection using ImmunoPure TMB substratekit (Pierce Biotechnology, Rockford, Ill.). The development of a yellowcolor, which correlated with the presence of the SNAP-25₁₉₇ cleavageproduct was detected in BoNT/A treated samples, but not untreatedcontrols, using antibody-containing serum derived from all six immunizedmice (Mouse 1, Mouse 2, Mouse 3, Mouse 4, Mouse 5, and Mouse 6). Thus,the comparative ELISA analysis indicated that of the mice used forimmunization, three mice (Mouse 2, Mouse 3, and Mouse 4) had highertiters and more specificity towards a SNAP-25 antigen having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond.

For cell-based cleavage assay, a suitable density of PC12 cells wereplated into 60 mm² tissue culture plates containing 3 mL of anappropriate serum medium (Table 1). The cells were grown in a 37° C.incubator under 5% carbon dioxide until cells reached the appropriatedensity. A 500 μL transfection solution was prepared by adding 250 μL ofOPTI-MEM Reduced Serum Medium containing 15 μL of LipofectAmine 2000(Invitrogen Inc., Carlsbad, Calif.) incubated at room temperature for 5minutes to 250 μL of OPTI-MEM Reduced Serum Medium containing 10 pg of apQBI-25/GFP-BoNT/A-LC expression construct (SEQ ID NO: 51). ThepQBI-25/GFP-BoNT/A-LC expression construct comprises a pQBI-25expression vector (Qbiogene Inc., Carlsbad, Calif.) whose promoterelements are functionally linked to a polynucleotide encoding theGFP-BoNT/A light chain of SEQ ID NO: 52. This transfection mixture wasincubated at room temperature for approximately 20 minutes. The mediawas replaced with fresh unsupplemented media and the 500 μL transfectionsolution was added to the cells. The cells were then incubated in a 37°C. incubator under 5% carbon dioxide for approximately 6 to 18 hours.The cells were washed and harvested as described in Example II. Todetect for the presence of the cleaved SNAP-25₁₉₇ product, an aliquotfrom each harvested sample was analyzed by Western blot as described inExample II, except that the primary antibody used was a 1:1,000 dilutionof the antibody-containing serum and the secondary antibody used was a1:20,000 of mouse α-IgG Horseradish Peroxidase (Pierce Biotechnology,Rockford, Ill.). A single band corresponding to the SNAP-25₁₉₇ cleavageproduct was detected in BoNT/A treated samples, but not untreatedcontrols, using antibody-containing serum derived from three mice (Mouse2, Mouse 3, and Mouse 4). Thus, the cell-based cleavage assay indicatedthat of the mice used for immunization, three mice (Mouse 2, Mouse 3,and Mouse 4) had higher titers and more specificity towards a SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond.

3. Production of Hybridomas.

To make hybridomas producing α-SNAP-25 monoclonal antibodies that canselectively bind to a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond, the spleen fromMouse 2 was harvested three days subsequent to a final “booster”immunization and the spleen cells were fused with myeloma cells P₃-X63Ag8.653 using standard hybridoma protocols. These cells were plated intofive 96-well plates and hybrids were selected using HAT medium. Within8-14 days after fusion, the first screening of the approximately 480parent clones was carried out using comparative ELISA with theBirA-HisTag®-SNAP-25₁₃₄₋₁₉₇ and the BirA-HisTag®-SNAP-25₁₃₄₋₂₀₆ peptidescoated in two separate plates. The comparative ELISA provided a quickscreen method to identify hybridomas producing antibodies specific forthe cleaved SNAP-25₁₉₇. The top 18 clones were subjected to furtherscreening using the cell-based cleavage assay described above andimmunostaining of LC/A transfected cells. (Table 7).

TABLE 7 Analysis of Supernatants Containing α-SNAP-25 MonoclonalAntibody Comparative ELISA Cell-Based Assay Clone OD SNAP-25₁₉₇ ODSNAP-25₂₀₆ Ratio_(197/206) Ratio_(206/197) SNAP-25₁₉₇ SNAP-25₂₀₆ 1D31.805 0.225 8.02 0.13 +++ − 1F12 0.365 0.093 3.92 0.25 − − 1G10 0.5900.137 4.31 0.23 ++ − 1H1 0.335 0.121 2.77 0.36 − − 1H8 0.310 0.302 1.030.97 + − 2C9 0.139 0.274 0.51 1.97 − − 2E2 0.892 0.036 24.78 0.04 ++ −2E4 0.228 0.069 3.30 0.30 + − 2F11 1.095 1.781 0.61 1.63 − − 3C1 1.2680.053 23.92 0.04 ++ − 3C3 0.809 0.052 15.56 0.06 ++ − 3E1 0.086 0.1550.55 1.80 0 − 3E8 2.048 0.053 38.64 0.03 +++ − 3G2 0.053 0.158 0.34 2.98− − 4D1 0.106 0.218 0.49 2.06 − − 4G6 0.061 0.159 0.38 2.61 − − 5A50.251 0.106 2.37 0.42 + − 5F11 0.243 0.061 3.98 0.25 − −

Clones 1D3, 1G10, 2E2, 3C1, 3C3, and 3E8 were further cloned by limitingdilution because the conditioned media produced by these clonescomprised α-SNAP-25 antibodies with a preferential binding specificityhaving a ratio_(197/206) of at least 4:1 for the SNAP-25₁₉₇ cleavageproduct relative to the SNAP-25₂₀₆ uncleaved substrate and detected theSNAP-25₁₉₇-cleavage product using the cell-based cleavage assay and theimmunostaining of PC12 cells transfected with GFP-LC/A. Similarly clones2C9, 2F11, 3G2, 4D1 and 4G6 were further cloned by limiting dilutionbecause the conditioned media produced by these clones comprisedα-SNAP-25 antibodies with a preferential binding specificity having aratio_(206/197) of at least 1.5:1 for the SNAP-25₂₀₆ uncleaved substraterelative to the SNAP-25₁₉₇ cleavage product and detected theSNAP-25₂₀₆-uncleaved substrate using the cell-based cleavage assay.These single-cell derived clones were screened again using comparativeELISA, cell-based cleavage, and immunostaining to confirm their affinityand specificity, and the antibodies were isotyped using standardprocedures. Ascites were produced from clones 1D3B8 (IgM.k), 1G10A12(IgG3.k), 2C9B10 (IgG3.k), 2E2A6 (IgG3.k), 2F11B6 (IgM.k), 3C1A5(IgG2a.k), and 3C3E2 (IgG2a.k). Clone 3E8 stopped producing antibodiesduring the cloning process and could not be further evaluated.

4. Evaluation of Binding Specificity of α-SNAP-25 Monoclonal Antibodies.

To evaluate binding specificity of an α-SNAP-25 monoclonal antibody thatcan selectively bind to a SNAP-25 antigen having a carboxyl-terminus atthe P₁ residue of the BoNT/A cleavage site scissile bond, ascites fromclones 1D3B8, 1G10A12, 2C9B10, 2E2A6, 2F11B6, 3C1A5, and 3C3E2 were usedto detect SNAP-25 cleavage product using the cell-based activity assay,immunocytochemistry and immunoprecipitation.

For the cell-based activity assay, binding specificity was determined byanalyzing the ability of α-SNAP-25 antibody-containing ascites to detectthe uncleaved SNAP-25₂₀₆ substrate and the cleaved SNAP-25₁₉₇ product byWestern blot analysis. A suitable density of PC12 cells were plated into60 mm² tissue culture plates containing 3 mL of an appropriate serummedium, grown in a 37° C. incubator under 5% carbon dioxide until anappropriate cell density was reached, and transfected with the either atransfection solution lacking the pQBI-25/GFP-BoNT/A-LC expressionconstruct (untransfected cells) or a transfection solution containingthe pQBI-25/GFP-BoNT/A-LC expression construct (transfected cells) asdescribed above. The cells were washed and harvested as described inExample I. To detect for the presence of both the uncleaved SNAP-25₂₀₆substrate and the cleaved SNAP-25₁₉₇ product, an aliquot from eachharvested sample was analyzed by Western blot as described in Example I,except that the primary antibody used was a 1:100 dilution of theα-SNAP-25 monoclonal antibody-containing ascites and the secondaryantibody used was a 1:20,000 of α-mouse IgG conjugated to HorseradishPeroxidase (Pierce Biotechnology, Rockford, Ill.). In addition, threecommercially available mouse α-SNAP-25 monoclonal antibodies weretested. SMI-81 (Sternberger Monoclonals Inc., Lutherville, Md.), anα-SNAP-25 antibody the manufacturer indicates detects both the uncleavedSNAP-25₂₀₆ substrate and the cleaved SNAP-25₁₉₇ product, was used at a15,000 dilution according to the manufacturer's recommendations. MC-6050(Research & Diagnostic Antibodies, Las Vegas, Nev.), an α-SNAP-25antibody the manufacturer indicates detects both the uncleavedSNAP-25₂₀₆ substrate and the cleaved SNAP-25₁₉₇ product, was used at a1:100 dilution according to the manufacturer's recommendations. MC-6053(Research & Diagnostic Antibodies, Las Vegas, Nev.), an α-SNAP-25antibody the manufacturer indicates detects only the cleaved SNAP-25₁₉₇product, was used at a 1:100 dilution according to the manufacturer'srecommendations.

Table 8 indicates the α-SNAP-25 antibody-containing ascites thatdetected only the SNAP-25₁₉₇ cleavage product. The cell-based cleavageassay indicated that ascites produced from clones 1D3B8, 2C9B10, 2E2A6,3C1A5, and 3C3E2 synthesize an α-SNAP-25 monoclonal antibody having highbinding specificity for the SNAP-25₁₉₇ cleavage product that allows forthe selective recognition of this cleavage product relative to theSNAP-25₂₀₆ uncleaved substrate. Commercial antibody SMI-81 detected theSNAP-25₂₀₆ uncleaved substrate, but only poorly recognized theSNAP-25₁₉₇ cleavage product (Table 8). Surprisingly, commercial antibodyMC-6050 only detected the SNAP-25₂₀₆ uncleaved substrate, and failed torecognize the SNAP-25₁₉₇ cleavage product (Table 8). Even moresurprisingly, commercial antibody MC-6050 only detected the SNAP-25₂₀₆uncleaved substrate, and failed to recognize the SNAP-25₁₉₇ cleavageproduct, even though the manufacturer advertises that this antibodyselectively detects the SNAP-25₁₉₇ cleavage product (Table 8). Thus,this analysis indicates that while 1D3B8, 2C9B10, 2E2A6, 3C1A5, and3C3E2 exhibit suitable selectivity for the SNAP-25₁₉₇ cleavage product,1G10A12 and 2F11B6 do not. In addition, commercial antibodies SMI-81,MC-6050 and MC-6053 all are unsuitable for the immuno-based methodsdisclosed in the present application because all failed to selectivitydetect the SNAP-25₁₉₇ cleavage product.

For immunocytochemistry analysis, binding specificity was determined byanalyzing the ability of α-SNAP-25 antibody-containing ascites to detectthe uncleaved SNAP-25₂₀₆ substrate and the cleaved SNAP-25₁₉₇ product byimmunostaining. See e.g., Ester Fernandez-Salas et al., Plasma MembraneLocalization Signals in the Light Chain of Botulinum Neurotoxin, Proc.Natl. Acad. Sci., U.S.A. 101(9): 3208-3213 (2004). A suitable density ofPC12 cells were plated, grown, and transfected with either atransfection solution lacking the pQBI-25/GFP-BoNT/A-LC expressionconstruct (untransfected cells) or a transfection solution containingthe pQBI-25/GFP-BoNT/A-LC expression construct (transfected cells) asdescribed above. The cells were washed in 1×PBS and fixed in 5 mL of PAFat room temperature for 30 minutes. Fixed cells were washed in phosphatebuffered saline, incubated in 5 mL of 0.5% Triton® X-100 (polyethyleneglycol octylphenol ether) in 1×PBS, washed in 1×PBS, and permeabilizedin 5 mL of methanol at −20° C. for six minutes. Permeabilized cells wereblocked in 5 mL of 100 mM glycine at room temperature for 30 minutes,washed in 1×PBS, and blocked in 5 mL of 0.5% BSA in 1×PBS at roomtemperature for 30 minutes. Blocked cells were washed in 1×PBS andincubated at room temperature for two hours in 0.5% BSA in 1×PBScontaining a 1:10 dilution of an ascites from a clonal hybridoma cellline being tested. Primary antibody probed cells were washed three timesfor 5 minutes each time in 1×PBS. Washed cells were incubated at roomtemperature for 2 hours in 1×PBS containing a 1:200 dilution of goatpolyclonal anti-mouse immunoglobulin G, heavy and light chains (IgG,H+L) antibody conjugated to ALEXA® FLUOR 568 (Invitrogen Inc., Carlsbad,Calif.) as a secondary antibody. Secondary antibody-probed cells werewashed three times for 5 minutes each time in 1×PBS. Washed cells wereprepared for microscopic examination by mounting in VECTASHIELD®Mounting Media (Vector Laboratories, Burlingame, Calif.) andcoverslipped. Images of signal detection were obtained with a Leicaconfocal microscope using appropriate laser settings. Table 8 indicatesthat the α-SNAP-25 antibody-containing ascites that specificallydetected the SNAP-25₁₉₇-cleavage product. The immunocytochemistryanalysis indicated that ascites produced from clones 1D3B8, 2C9B10,2E2A6, 3C1A5, and 3C3E2 synthesize an α-SNAP-25 monoclonal antibodyhaving high binding specificity for the SNAP-25₁₉₇ cleavage product thatallows for the preferential recognition of this cleavage productrelative to the SNAP-25₂₀₆ uncleaved substrate.

For immunoprecipitation analysis, binding specificity was determined byanalyzing the ability of Protein A (HiTrap™ Protein A HP Columns, GEHealthcare, Amersham, Piscataway, N.J.), purified α-SNAP-25 monoclonalantibodies to precipitate the uncleaved SNAP-25₂₀₆ substrate and thecleaved SNAP-25₁₉₇ product. See e.g., Chapter 8 Storing and PurifyingAntibodies, pp. 309-311, Harlow & Lane, supra, 1998a. A suitable densityof PC12 cells were plated, grown, and transfected with either atransfection solution containing a pQBI-25/GFP expression construct(control cells; SEQ ID NO: 53) or a transfection solution containing thepQBI-25/GFP-BoNT/A-LC expression construct (experimental cells) asdescribed above. The pQBI-25/GFP expression construct comprises anexpression vector whose promoter elements are functionally linked to apolynucleotide encoding GFP of SEQ ID NO: 54. After an overnightincubation, the cells were washed by aspirating the growth media andrinsing each well with 200 μl 1×PBS. To harvest the cells, the PBS wasaspirated, the cells were lysed by adding an Immunoprecipitation LysisBuffer comprising 50 mM HEPES, 150 mM NaCl, 1.5 mM MgCl₂, 1 mM EGDT, 10%glycerol, 1% Triton® X-100 (polyethylene glycol octylphenol ether) and a1× COMPLETE™ Protease inhibitor cocktail (Roche Applied Biosciences,Indianapolis, Ind.) and incubating at 4° C. for one hour. The lysedcells were centrifuged at 3,000×g at 4° C. for 10 minutes to removecellular debris and the supernatant transferred to a clean tube anddiluted to a protein concentration of approximately 1 mg/mL.Approximately 5 pg of purified monoclonal antibody was added to 0.5 mLof diluted supernatant and incubated at 4° C. for two hours. Afterprimary antibody incubation, approximately 50 μl of immobilized ProteinG (Pierce Biotechnology, Rockford, Ill.) was added to the dilutedsupernatant and incubated at 4° C. for one hour. The incubatedsupernatant was washed three times for 30 minutes each time by adding0.5 mL of Immunoprecipitation Lysis Buffer, centrifuging at 300×g at 4°C. for one minute to pellet the immobilized Protein G, and decanting thesupernatant. After washing, the pellet was resuspended in 30 μl of 1×SDSLoading Buffer and the sample was heated to 95° C. for 5 minutes. Todetect for the presence of both the uncleaved SNAP-25₂₀₆ substrate andthe cleaved SNAP-25₁₉₇ product, an aliquot from each harvested samplewas analyzed by Western blot as described in Example I, except that theprimary antibody used was a 1:1,000 dilution of the α-SNAP-25 polyclonalantibody serum (see Example IV) and the secondary antibody used was a1:20,000 of rabbit α-IgG Horseradish Peroxidase (Pierce Biotechnology,Rockford, Ill.). Table 8 indicates the α-SNAP-25 antibody-containingascites that specifically pulled down the SNAP-25₁₉₇-cleavage product byimmunoprecipitation analysis. The immunoprecipitation analysis indicatedthat ascites produced from clones 2E2A6 and 3C1A5 synthesize anα-SNAP-25 monoclonal antibody having high binding specificity for theSNAP-25₁₉₇ cleavage product that allows for the preferential recognitionof this cleavage product relative to the SNAP-25₂₀₆ uncleaved substrate.

TABLE 8 Analysis of Clone Ascites Containing α-SNAP-25 MonoclonalAntibody Cell-Based Assay Immunocytochemistry Immunoprecipitation CloneSNAP-25₁₉₇ SNAP-25₂₀₆ SNAP-25₁₉₇ SNAP-25₂₀₆ SNAP-25₁₉₇ SNAP-25₂₀₆ 1D3B8++ − ++ − Not Tested Not Tested 1G10A12 ++ ++ Not Tested Not Tested NotTested Not Tested 2C9B10 ++ − ++ − Not Tested Not Tested 2E2A6 ++ − ++ −++ − 2F11B6 + + + + Not Tested Not Tested 3C1A5 ++ − ++ − ++ − 3C3E2 + −Not Tested Not Tested Not Tested Not Tested MC-6050 − + Not Tested NotTested Not Tested Not Tested MC-6053 − + Not Tested Not Tested NotTested Not Tested SMI-81 −/+ ++ Not Tested Not Tested Not Tested NotTested

5. Evaluation of Binding Affinity of α-SNAP-25 Monoclonal Antibodies.

To determine the binding affinity of an α-SNAP-25 monoclonal antibodyshowing high binding specificity for either the SNAP-25₁₉₇ cleavageproduct or the SNAP-25₂₀₆ uncleaved substrate, binding affinity assayswere performed on a BIAcore™ 3000 instrument using carboxymethyl dextran(CM5) sensor chips (BIAcore, Inc., Piscataway, N.J.). Runs wereconducted at 25° C. with HBS-EP buffer comprising 10 mM HEPES (pH 7.4),150 mM sodium chloride, 3 mM EDTA, 0.005% (v/v) surfactant P₂₀ at a flowrate of 10 μl/min. SNAP-25 peptides comprising amino acids 134-197 ofSEQ ID NO: 5 (SNAP-25₁₃₄₋₁₉₇) or amino acids 134-206 of SEQ ID NO: 5(SNAP-25₁₃₄₋₂₀₆) were covalently attached to the surface of the CM5sensor chips using standard amine coupling. Briefly, the CM5 chips wereactivated by a 7 minute injection of a mixture of 0.2 M1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and 0.05 MN-hydroxysuccimide; the SNAP-25 peptides were then injected in 10 mMsodium acetate (pH 4.0) for 20 min at a flow rate of 10 μL/min; andunreacted succimide esters were blocked by a 7-min injection of 1 Methanolamine hydrochloride, pH 8.5. The immobilized amount ofSNAP-25₁₃₄₋₁₉₇ or SNAP-25₁₃₄₋₂₀₆ on the chip was reflected by a 100-150increase in response units (about 0.10-0.15 ng/mm²). Antibody samplescomprising either ascites or purified monoclonal antibodies producedfrom clones 1D3B8, 2C9B10, 2E2A6, 3C1A5, and 3C3E2, as well as,commercially available α-SNAP-25 antibodies were passed over the surfaceof the CM5 chips allowing an association time of 10 min and adissociation time of 20 min. The surfaces were regenerated between runsby a 1 minute injection of 10 mM glycine-HCl (pH 2.5) at a flow rate of15 μL/min. Sensorgram curves were fitted to a 1:1 kinetic binding modelwith the BIAevaluation™ 3.0 software.

The results indicate that both 2E2A6 and 3C1A5 were highly specific forcleaved SNAP-25₁₉₇ product over SNAP-25 uncleaved substrate (Table 9).When compared to the binding affinities of MC-6050 and MC-6053, 1D3B6had an approximately 10-fold higher equilibrium disassociation constantfor the SNAP-25 cleavage product relative to these commercial antibodies(Table 9). Interestingly, 2E2A6 had only a slightly lower equilibriumdisassociation constant for the SNAP-25 cleavage product relative tothese commercial antibodies (0.405 nM versus 0.497 and 0.508)(Table 9).As neither of these commercial α-SNAP-25 antibodies selectivelyrecognized the SNAP-25 cleavage product (Table 8), an equilibriumdisassociation constant lower than about 0.5 nM appears, in part,critical to achieve such selectivity. Similarly, when compared to thebinding affinities of MC-6050 and MC-6053, 2E2A6 had an about at leastone-fold slower off rate/dissociation constant (6.74×10⁻⁵ versus8.82×10⁻⁴ s⁻¹ and 1.18×10⁻³ s⁻¹) (Table 9). This further suggests thatan off rate/dissociation constant lower than about 8.82×10⁻⁴ appears, inpart, critical to achieve selective binding for the SNAP-25 cleavageproduct. This result is consistent with 1D3B8, which had an offrate/dissociation constant of 5.78×10⁻⁵ s⁻¹ (Table 9).

TABLE 9 Analysis of Binding Affinity α-SNAP-25 Monoclonal Antibodies SPR1D3B8 2E2A6* Parameter SNAP-25₁₉₇ SNAP-25₂₀₆ ^(a) SNAP-25₁₉₇ SNAP-25₂₀₆^(b) Ka (M⁻¹ s⁻¹) 1.06 × 10⁶   — 1.70 × 10⁶   — (1.66 × 10⁵)   (—) Kd(s⁻¹) 5.78 × 10⁻⁵ — 1.53 × 10⁻⁴ — (6.74 × 10⁻⁵) (—) KD (nM) 0.050 —0.090 — (0.405) (—) SPR 3C1A5 2C9B10 Parameter SNAP-25₁₉₇ SNAP-25₂₀₆^(c) SNAP-25₁₉₇ SNAP-25₂₀₆ ^(d) Ka (M⁻¹ s⁻¹) 2.17 × 10⁵   — 1.15 × 10⁴  — Kd (s⁻¹) 2.88 × 10⁻⁴ — 3.11 × 10⁻⁴ — KD (nM) 1.33 — 27.1 — SPR MC-6050MC-6053 Parameter SNAP-25₁₉₇ SNAP-25₂₀₆ SNAP-25₁₉₇ SNAP-25₂₀₆ Ka (M⁻¹s⁻¹) 1.78 × 10⁶   3.06 × 10²   2.32 × 10⁶   1.06 × 10²   Kd (s⁻¹) 8.82 ×10⁻⁴ 6.07 × 10⁻³ 1.18 × 10⁻³ 2.56 × 10⁻⁵ KD (nM) 0.497 19,800 0.508 240*Two independent runs were conducted for this antibody with twodifferent chips. ^(a)No binding was observed when up to 125 nM ofα-SNAP-25 monoclonal antibody 1D3B8 was passed over the surface of theCM5 sensor chip after a 10 minute association time. ^(b)No binding wasobserved when up to 10 μM of α-SNAP-25 monoclonal antibody 2E2A6 waspassed over the surface of the CM5 sensor chip after a 10 minuteassociation time. ^(C)No binding was observed when up to 100 nM ofα-SNAP-25 monoclonal antibody 3C1A5 was passed over the surface of theCM5 sensor chip after a 10 minute association time. ^(d)No binding wasobserved when up to 100 nM of α-SNAP-25 monoclonal antibody 2C9B10 waspassed over the surface of the CM5 sensor chip after a 10 minuteassociation time.6. Sequencing of the Epitope from Isolated α-SNAP-25 MonoclonalAntibodies.

To determine the epitope of an isolated α-SNAP-25 monoclonal antibodythat can selectively bind to a SNAP-25 antigen having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond, the polynucleotide molecule encoding the variable heavy (V_(H))and variable light (V_(L)) chains of the α-SNAP-25 monoclonal antibodyproduced by hybridomas 1D3B8, 2C9B10, 2E2A6, 3C1A5 and 3C3E2 weresequenced. mRNA was extracted and purified from each hybridoma usingstandard protocols and reversed transcribed into cDNA using either anoligo dT anti-sense primer or a gene-specific (murine IgG1 CH and kappaCL) anti-sense primer. Specific murine and human constant domain primerswere used to amplify the cDNA by PCR after cDNA production to determinethe isotype of the antibody. Degenerate V_(H) and V_(L) primers wereused to amplify the variable domains from the cDNA. For 5′RACE, ahomopolymeric dCTP tail was added to the 3′ end of the cDNA. The heavyand light chains were then amplified with an oligo dG sense primer and agene specific (CH/KC) anti-sense primer. PCR products included thesequence of the signal peptide, variable domains and constant domains upto the anti-sense primer. The PCR products were gel purified to removesmall fragments, and cloned into a blunt or TA vector for sequencing.Five independent clones for each chain were sequenced and alignments ofV_(H) and V_(L) chains and consensus sequences were determined (Table10). Methods used to determine the V_(H) and V_(L) amino acid sequencesare described in, e.g., Roger A. Sabbadini, et al., Novel BioactiveLipid Derivatives and Methods of Making and Using Same, U.S. PatentPublication 2007/0281320; and Peter Amersdorfer, et al., MolecularCharacterization of Murine Humoral Immune Response to BotulinumNeurotoxin Type A Binding Domain as Assessed by Using Phage AntibodyLibraries, 65(9) Infect. Immun. 3743-3752, each of which is herebyincorporated by reference in its entirety. In addition, commercialservices are available to sequence the variable heavy (V_(H)) andvariable light (V_(L)) chains of an antibody and identify the CDRregions, see, e.g., Fusion Antibodies Ltd., Northern Ireland.

The polynucleotide sequence comprising the V_(H) and V_(L) chains of theα-SNAP-25 monoclonal antibody produced by the hybridomas disclosed inthe present specification is as follows: 1D3B8 V_(H) (SEQ ID NO: 71),2C9B10 V_(H) (SEQ ID NO: 73), 2E2A6 V_(H) (SEQ ID NO: 75), 3C1A5 V_(H)variant 1 (SEQ ID NO: 77), 3C1A5 V_(H) variant 2 (SEQ ID NO: 79), 3C3E2V_(H) (SEQ ID NO: 81); 1D3B8 V_(L) (SEQ ID NO: 83), 2C9B10 V_(L) (SEQ IDNO: 85), 2E2A6 V_(L) (SEQ ID NO: 87), 3C1A5 V_(L) (SEQ ID NO: 89), and3C3E2 V_(L) (SEQ ID NO: 91). The amino acid sequence comprising theV_(H) and V_(L) chains of the α-SNAP-25 monoclonal antibody produced bythe hybridomas disclosed in the present specification is as follows:1D3B8 V_(H) (SEQ ID NO: 72), 2C9B10 V_(H) (SEQ ID NO: 74), 2E2A6 V_(H)(SEQ ID NO: 76), 3C1A5 V_(H) variant 1 (SEQ ID NO: 78), 3C1A5 V_(H)variant 2 (SEQ ID NO: 80), 3C3E2 V_(H) (SEQ ID NO: 82); 1D3B8 V_(L) (SEQID NO: 84), 2C9B10 V_(L) (SEQ ID NO: 86), 2E2A6 V_(L) (SEQ ID NO: 88),3C1A5 V_(L) (SEQ ID NO: 90), and 3C3E2 V_(L) (SEQ ID NO: 92). The aminoacid sequences comprising the V_(H) and V_(L) CDR domains of theα-SNAP-25 monoclonal antibody produced by the hybridomas 1D3B8, 2C9B10,2E2A6, 3C1A5, and 3C3E2 are given in Table 10.

TABLE 10 CDR Sequences of V_(H )and V_(L )domains fromα-SNAP-25 Monoclonal Antibodies SEQ CDR Sequence Identified In ID NO:V_(H )CDR 1 TFTDHSIH 2E2A6 93 2C9B10 3C1A5 variant 2 V_(H )CDR 1TFTNYVIH 3C1A5 variant 1 94 3C3E2 V_(H )CDR 1 IFTDHALH 1D3B8 95V_(H )CDR 2 YIFPGNGNIEYNDKFKG 2E2A6 96 V_(H )CDR 2 YLFPGNGNFEYNEKFKG2C9B10 97 3C1A5 variant 2 V_(H )CDR 2 YINPYNDGSKYNEKFKG 3C1A5 variant 198 3C3E2 V_(H )CDR 2 YIFPGNGNIEYNEKFKG 1D3B8 99 V_(H )CDR 3 KRMGY 2E2A6100 3C1A5 variant 2 V_(H )CDR 3 KKMDY 2C9B10 101 1D3B8 V_(H )CDR 3ARHLANTYYYFDY 3C1A5 variant 1 102 3C3E2 V_(L )CDR 1 RSSQSIVHSNGNTYLE1D3B8 103 V_(L )CDR 1 RTTENIYSYFV 2C9B10 104 V_(L )CDR 1 RASKSVSTSGYSYMH2E2A6 105 V_(L )CDR 1 KASQDIKSYLS 3C1A5 106 V_(L )CDR 1 RASQNIGNYLH3C3E2 107 V_(L )CDR 2 KVSNRFS 1D3B8 108 V_(L )CDR 2 NAKSLAE 2C9B10 109V_(L )CDR 2 LVSNLES 2E2A6 110 V_(L )CDR 2 YATSLAD 3C1A5 111 V_(L )CDR 2YASQSIS 3C3E2 112 V_(L )CDR 3 FQGSHVPPT 1D3B8 113 V_(L )CDR 3 QHHYGTPYT2C9B10 114 V_(L )CDR 3 QHIRELTRS 2E2A6 115 V_(L )CDR 3 LQHGESPFT 3C1A5116 V_(L )CDR 3 QQSDTWPLT 3C3E2 117

Non-limiting examples of amino acid sequences comprising V_(H) CDRdomain variants of the α-SNAP-25 monoclonal antibody produced by thehybridomas disclosed in the present specification include V_(H) CDR1variant SEQ ID NO: 118 for 1D3B8; V_(H) CDR1 variant SEQ ID NO: 119 for2C9B10, 2E2A6 and 3C1A5 V_(H) variant 2; V_(H) CDR1 variant SEQ ID NO:120 for 3C1A5 V_(H) variant 1 and 3C3E2; V_(H) CDR2 variant SEQ ID NO:121 for 1D3B8 and 2E2A6; V_(H) CDR2 variant SEQ ID NO: 122 for 2C9B10and 3C1A5 V_(H) variant 2; V_(H) CDR2 variant SEQ ID NO: 123 for 3C1A5V_(H) variant 1, and 3C3E2; V_(H) CDR3 variant MDY for 1D3B8 and 2C9B10;V_(H) CDR3 variant MGY for 2E2A6 and 3C1A5 V_(H) variant 2; and V_(H)CDR3 variant SEQ ID NO: 124 for 3C1A5 V_(H) variant 1 and 3C3E2.Non-limiting examples of amino acid sequences comprising V_(L) CDRdomain variants of the α-SNAP-25 monoclonal antibody produced by thehybridomas disclosed in the present specification include V_(L) CDR1variant SEQ ID NO: 125 for 1D3B8; V_(L) CDR1 variant SEQ ID NO: 126 for2C9B10; V_(L) CDR1 variant SEQ ID NO: 127 for 2E2A6; V_(L) CDR1 variantSEQ ID NO: 128 for 3C1A5; V_(L) CDR1 variant SEQ ID NO: 129 for 3C3E2;V_(L) CDR2 variant KVS for 1D3B8; V_(L) CDR2 variant NAK for 2C9B10;V_(L) CDR2 variant LVS for 2E2A6; V_(L) CDR2 variant YAT for 3C1A5; andV_(L) CDR2 variant YAS for 3C3E2.

Example IV Development of α-SNAP-25 Polyclonal Antibodies thatSelectively Bind a SNAP-25 Epitope Having a Free Carboxyl-Terminus atthe P₁ Residue of the BoNT/a Cleavage Site Scissile Bond

The following example illustrates how to make α-SNAP-25 polyclonalantibodies that can selectively bind to a SNAP-25 epitope having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond.

To develop α-SNAP-25 polyclonal antibodies that bind an epitopecomprising a carboxyl-terminus at the P1 residue from the BoNT/Acleavage site scissile bond from a SNAP-25 cleavage product, the10-residue peptide CGGGRIDEANQ (SEQ ID NO: 46) was designed as a SNAP-25cleavage product antigen. This peptide comprising a N-terminal Cysteineresidue for conjugation to KLH, a G-spacer flexible spacer (GGG) linkedto amino acids 191-197 of human SNAP-25 (SEQ ID NO: 5) and has acarboxylated C-terminal glutamine. Blast searches revealed that thispeptide has high homology only to SNAP-25 and almost no possiblecross-reactivity with other proteins in neuronal cells. The sequence wasalso carefully scrutinized by utilizing computer algorithms to determinehydropathy index, protein surface probability, regions of flexibility,and favorable secondary structure, followed by proper orientation andpresentation of the chosen peptide sequence. The peptide was synthesizedand conjugated to Keyhole Limpet Hemocyanin (KLH) to increaseimmunogenicity. Before the animals were immunized, naïve rabbits werefirst screened against cell lysates from candidate cell lines in aWestern blot in order to identify animals that had no immunoreactivityto the proteins present in the cell lysates. Two pre-screened rabbitswere immunized with this peptide, and after three immunizations in abouteight weeks, the rabbits were bled for testing. The blood was allowed toclot by incubating at 4° C. for 60 minutes. The clotted blood wascentrifuged at 10,000×g at 4° C. for 10 minutes to pellet the cellulardebris. The resulting serum sample was dispensed into 50 μL aliquots andstored at −20° C. until needed.

A similar strategy based on other SNAP-25 antigens disclosed in thepresent specification is used to develop α-SNAP-25 polyclonal antibodiesthat bind an epitope comprising a carboxyl-terminus at the P₁ residuefrom the BoNT/A cleavage site scissile bond from a SNAP-25 cleavageproduct. For example, the SNAP-25 antigen of SEQ ID NO: 47 can beconjugated to KLH instead of the SNAP-25 antigen of SEQ ID NO: 46. Asanother example, the amino acids 191-197 of human SNAP-25 from theSNAP-25 antigen of SEQ ID NO: 38 can be replaced with SEQ ID NO: 33, SEQID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 39,SEQ ID NO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, SEQ ID NO:44, SEQ ID NO: 147 or SEQ ID NO: 148.

2. Screening for the Presence of α-SNAP-25 Polyclonal Antibodies.

To determine the presence of α-SNAP-25 polyclonal antibodies that canselectively bind to a SNAP-25 antigen having a carboxyl-terminus at theP₁ residue of the BoNT/A cleavage site scissile bond, comparative ELISAand cell-based cleavage assays were performed using the extracted rabbitserum as described in Example III. The serum from both rabbits containedα-SNAP-25 polyclonal antibodies that can selectively bind to a SNAP-25antigen having a carboxyl-terminus at the P₁ residue of the BoNT/Acleavage site scissile bond. The α-SNAP-25 rabbit polyclonal antibodieswere designated as NTP 22 and NTP 23.

3. Purification of α-SNAP-25 Polyclonal Antibodies.

To purify α-SNAP-25 polyclonal antibodies that can selectively bind to aSNAP-25 antigen having a carboxyl-terminus at the P₁ residue of theBoNT/A cleavage site scissile bond, NTP 22 and NTP 23 antibodies fromrabbit serum were purified using affinity columns containing the SNAP-25antigen of SEQ ID NO: 46.

4. Evaluation of Binding Specificity of α-SNAP-25 Polyclonal Antibodies.

To evaluate binding specificity of an α-SNAP-25 polyclonal antibody thatcan selectively bind to a SNAP-25 antigen having a carboxyl-terminus atthe P₁ residue of the BoNT/A cleavage site scissile bond, purified NTP22 and NTP 23 α-SNAP-25 polyclonal antibodies were used to detectcleavage product using the cell-based activity assay,immunnocytochemistry and immunoprecipitation as described in ExampleIII. The cell-based cleavage assay, immunocytochemistry analysis andimmunoprecipitation analysis all indicated that NTP 22 and NTP 23α-SNAP-25 polyclonal antibodies did not cross-react with uncleavedSNAP-25. Thus both NTP 22 and NTP 23 have high binding specificity forthe SNAP-25₁₉₇ cleavage product that allows for the preferentialrecognition of this cleavage product relative to the SNAP-25₂₀₆uncleaved substrate. Affinity for the antigens can be determined usingSPR in the BiAcore as described in Example III.

Example V Component and Condition Preparation for a Sandwich ELISA

The following example illustrates how to identify and prepare thecomponents and conditions necessary to perform a sandwich ELISA usefulfor conducting immuno-based methods of detecting BoNT/A activity bydetecting a SNAP-25 cleavage product using a α-SNAP-25 monoclonalantibody specific for a SNAP-25 having a carboxyl-terminus at the P₁residue of the BoNT/A cleavage site scissile bond.

1. Preparation of Cell Lysates from Cells Treated with BoNT/A.

To obtain a BoNT/A treated cell lysate for analysis, a suitable densityof cells from a stock culture of Neuro-2a was seeded into a T175 flaskcontaining 50 mL of a serum-free medium containing Minimum EssentialMedium, 2 mM GlutaMAX™ I with Earle's salts, 1×B27 supplement, 1×N2supplement, 0.1 mM Non-Essential Amino Acids, 10 mM HEPES. These cellswere incubated in a 37° C. incubator under 5% carbon dioxide until thecells differentiated, as assessed by standard and routine morphologicalcriteria, such as growth arrest and neurite extension (approximately 2to 3 days). As a control, a suitable density of cells from a stockculture of Neuro-2a was seeded into a T175 flask containing 50 mL of anappropriate growth medium (Table 1). These undifferentiated controlcells were grown in a 37° C. incubator under 5% carbon dioxide until 50%confluence was reached (approximately 18 hours). The media from bothdifferentiated and undifferentiated control cultures was aspirated fromeach well and replaced with fresh media containing either 0 (untreatedsample) or 10 nM of a BoNT/A complex. After an overnight incubation, thecells were washed and the cells harvested by lysing in freshly preparedTriton X-100 Lysis Buffer (50 mM HEPES, 150 mM NaCl, 1.5 mM MgCl₂, 1 mMEGTA, 1% Triton X-100) at 4° C. for 30 minutes with constant agitation.Lysed cells were centrifuged at 4000 rpm for 20 min at 4° C. toeliminate debris using a bench-top centrifuge. The proteinconcentrations of cell lysates were measured by Bradford assay.

2. Preparation and Identification of Sandwich ELISA Components.

To identify an appropriate capture antibody-detection antibody pair anECL sandwich ELISA analysis was conducted on twenty-six differentcombinations of capture and detection antibody pairs comprising elevendifferent α-SNAP-25 capture antibodies and seven different α-SNAP-25detection antibodies (Table 12). The α-SNAP-25 antibodies used were2E2A6 and 3C1A5 α-SNAP-25 mouse monoclonal antibodies disclosed in thepresent specification, SMI-81, MC-6050, and MC-6053 α-SNAP-25 mousemonoclonal antibodies disclosed in the present specification, NTP 23α-SNAP-25 rabbit polyclonal antibodies disclosed in the presentspecification, S9684 α-SNAP-25 rabbit polyclonal antibodies (Sigma, St.Louis, Mo.), H-50 α-SNAP-25 rabbit polyclonal antibodies (Santa CruzBiotechnology, Inc., Santa Cruz, Calif.), C-18 α-SNAP-25 goat polyclonalantibodies (Santa Cruz Biotechnology, Inc., Santa Cruz, Calif.), N-19α-SNAP-25 goat polyclonal antibodies (Santa Cruz Biotechnology, Inc.,Santa Cruz, Calif.), and SP12 α-SNAP-25 mouse polyclonal antibodies(Santa Cruz Biotechnology, Inc., Santa Cruz, Calif.).

To prepare the capture antibody solution, the α-SNAP-25 monoclonalantibodies contained in the ascites from hybridoma cell lines 2E2A6 and3C1A5 as well as the α-SNAP-25 MC-6050 and MC-6053 monoclonal antibodieswere purified using a standard Protein A purification protocol. Allother α-SNAP-25 antibodies were purchased as purified antibodies.

To prepare the detection antibody solution, the appropriate α-SNAP-25antibody was conjugated toRuthenium(II)-tris-bipyridine-(4-methysulfonate) NHS ester labelingreagent (Meso Scale Discovery, Gaithersburg, Md.) according to themanufacturer's instructions (Meso Scale Discovery, Gaithersburg, Md.).The conjugation reaction was performed by adding 30 μL of distilledwater reconstituted MSD SULFO-TAG™ stock solution to 200 μL of 2 mg/mLα-SNAP-25 polyclonal antibodies and incubating the reaction at roomtemperature for 2 hours in the dark. The labeled antibodies werepurified using a standard spin column protocol and the proteinconcentration determined using a standard colorimetric protein assay.The absorbance of the α-SNAP-25 antibody/MSD SULFO-TAG™ conjugate wasmeasured at 455 nm using a spectrophotometer to determine theconcentration in moles per liter. The detection antibody solution wasstored at 4° C. until needed.

To prepare the solid phase support comprising the capture antibody thatis specific for a SNAP-25 cleavage product, approximately 5 μL of theappropriate α-SNAP-25 monoclonal antibody solution (20 μg/mL in 1×PBS)is added to each well of a 96-well MSD High Bind plate and the solutionis allowed to air dry in a biological safety cabinet for 2-3 hours inorder to liquid evaporate the solution. The capture antibody-bound wellswere then blocked by adding 150 μL of Blocking Buffer comprising 2%Amersham Blocking Reagent (GE Life Sciences, Piscataway, N.J.) and 10%goat serum (VWR, West Chester, Pa.) at room temperature for 2 hours.Blocked plates were sealed and stored at 4° C. until needed.

To detect the presence of a cleaved SNAP-25 cleavage product by ECLsandwich ELISA analysis, the Blocking Buffer from stored plates wasaspirated from the wells, 25 μL of a lysate from cells treated withBoNT/A, as described above, was added to each well and the plates wereincubated at 4° C. for overnight. Plate wells were washed three times byaspirating the cell lysate and rinsing each well three times with 200 μL1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate).After washing, 25 μl of 5 μg/mL detection antibody solution comprising2% Amersham Blocking Reagent in 1×PBS, 0.1% TWEEN-20® (polyoxyethylene(20) sorbitan monolaureate) was added to each well, the plate wassealed, and the sealed plate was incubated at room temperature at roomtemperature for 1 hour with shaking. After detection antibodyincubation, the wells were washed three times with 200 μL 1×PBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). After washing150 μL of 1×Read Buffer (Meso Scale Discovery, Gaithersburg, Md.) wasadded to each well and the plates were read using a SECTOR™ Imager 6000Image Reader (Meso Scale Discovery, Gaithersburg, Md.). A ratio wascalculated by dividing the signal obtained at the 10 nM dose for eachantibody-pair by the signal obtained at the 0 nM dose for eachantibody-pair (Table 12). These results indicated that among thetwenty-six different combinations of antibody pairs tested, only threeantibody pairs had signal-to-noise ratios above 10:1 for the higher dosetested: Pair No. 1 (2E2A6 mouse mAb and S9684 rabbit pAb), Pair No. 4(3C1A5 mouse mAb and S9684 rabbit pAb), and Pair No. 18 (S9684 rabbitpAb and 2E2A6 mouse mAb). Antibody Pair 1 was chosen for further assaydevelopment.

TABLE 12 Screening of α-SNAP-25 Antibody Combinations DetectionDetection Signal/Noise SNAP-25 SNAP-25 Ratio Antibody Capture Detectioncleavage uncleaved (10 nm/0 Pair No. Antibody Antibody product substratenM) 1 2E2A6 mouse S9684 rabbit pAb Yes No 26.6:1  mAb 2 2E2A6 mouse N-19goat pAb Yes No 7.3:1 mAb 3 2E2A6 mouse H-50 rabbit pAb Yes No 0.9:1 mAb4 3C1A5 mouse S9684 rabbit pAb Yes No 12.1:1  mAb 5 3C1A5 mouse N-19goat pAb Yes No 1.9:1 mAb 6 3C1A5 mouse H-50 rabbit pAb Yes No 0.9:1 mAb7 C-18 goat pAb S9684 rabbit pAb No No 0.8:1 8 C-18 goat pAb N-19 goatpAb No No 0.9:1 9 C-18 goat pAb H-50 rabbit pAb No No 0.9:1 10 H-50rabbit pAb 2E2A6 mouse Yes No 0.9:1 mAb 11 H-50 rabbit pAb C-18 goat pAbNo No 1.0:1 12 N-19 goat pAb 2E2A6 mouse Yes No 0.9:1 mAb 13 N-19 goatpAb C-18 goat pAb No No 1.1:1 14 NTP 23 rabbit pAb N-19 goat pAb Yes No1.2:1 15 NTP 23 rabbit pAb C-18 goat pAb No No 1.1:1 16 NTP 23 rabbitpAb SP12 mouse pAb Yes No 1.3:1 17 NTP 23 rabbit pAb H-50 rabbit pAb YesNo 1.1:1 18 S9684 rabbit pAb 2E2A6 mouse Yes No 21.3:1  mAb 19 S9684rabbit pAb C-18 goat pAb No No 0.7:1 20 S9684 rabbit pAb SMI-81mouse YesYes 1.2:1 mAb 21 SMI-81 mouse S9684 rabbit pAb Yes Yes 1.1:1 mAb 22SMI-81 mouse N-19 goat pAb Yes Yes 1.0:1 mAb 23 SMI-81 mouse C-18 goatpAb No No 0.8:1 mAb 24 SP12 mouse pAb C-18 goat pAb No No 1.0:1 25MC-6050 mouse S9684 rabbit pAb Yes Yes 5.0:1 mAb 26 MC-6053 mouse S9684rabbit pAb Yes Yes 7.1:1 mAb

3. Optimization of Cell Differentiation Conditions.

To determine the optimal differentiation condition for a cell linecomprising cells susceptible to BoNT/A intoxication when using asandwich ELISA detection system, both various cell culture media andlength of differentiation time were tested.

To determine an optimal differentiation medium, a suitable density ofcells from a SiMa cell line was plated into the wells of Collagen IVcoated 24-well cell culture plates containing 1 mL of one of thefollowing medias and differentiation supplements: 1) RPMI 1640, 10%fetal bovine serum, 1% Penicillin-Streptomycin, 2 mM L-Glutamine, and 25μg/mL GT1b); 2) RPMI-1640, 1×B27 supplement, 1×N2 supplement, and 25μg/mL GT1b; 3) Minimum Essential Medium, 1×B27 supplement, 1×N2supplement, and 25 μg/mL GT1b; and 4) RPMI-1640, 10% BSA, 1×N2supplement, 1×NGF supplement, and 25 μg/mL GT1b. Cells were incubated ina 37° C. incubator under 5% carbon dioxide until the cellsdifferentiated, as assessed by standard and routine morphologicalcriteria, such as growth arrest and neurite extension (approximately 3days). The media was aspirated from each well and replaced with freshmedia containing either 0 (untreated sample), 0.2 pM, 2 pM, or 20 pM ofa BoNT/A complex. After an overnight treatment, the cells were washed,incubated for an additional two days without toxin to allow for thecleavage of the SNAP-25 substrate, and harvested as described above inSection 1. The protein concentrations of cell lysates were measured byBradford assay. Detection of the presence of cleaved SNAP-25 product byECL sandwich ELISA analysis was performed as described above usingAntibody Pair 1. As discussed in Example I, undifferentiated cells didnot take up toxin as effectively as differentiated cells. The mosteffective differentiation medium for increasing BoNT/A uptake andconsequently SNAP-25 cleavage medium 3 (MEM+N2+B27), followed by medium2 (RPMI-1640+N2+B27), and medium 4 (RPMI-1640+N2+NGF+BSA) (FIG. 3).Cells cultured in medium 2 resulted in more cleavage of the SNAP-25 ascompared to the other media.

To determine an optimal differentiation time, a suitable density ofcells from a SiMa cell line was plated into the wells of poly-D-lysinecoated 96-well cell culture plates containing 100 μL of a serum-freemedium containing Minimum Essential Medium, 2 mM GlutaMAX™ I withEarle's salts, 1×B27 supplement, 1×N2 supplement, 0.1 mM Non-EssentialAmino Acids, 10 mM HEPES and 25 μg/mL GT1b. Cells were plated at fourdifferent days to obtain a differentiation time course testing 6 hrs, 24h, 48 hrs, and 72 hrs, and were incubated in a 37° C. incubator under 5%carbon dioxide The media was aspirated from each well and replaced withfresh media containing either 0 (untreated sample), 0.1 pM, 0.2 pM, 0.4pM, 0.8 pM, 1.6 pM, 3.1 pM, 6.25 pM, 12.5 pM, or 25 pM of a BoNT/Acomplex. After an overnight treatment, the cells were washed, incubatedfor an additional two days without toxin to allow for the cleavage ofthe SNAP-25 substrate, and harvested as described above in Section 1.After harvesting, the protein concentrations of cell lysates anddetection of the presence of cleaved SNAP-25 product by ECL sandwichELISA analysis were performed as described above. The raw data obtainedfrom the ECL imager was then transferred to SigmaPlot v. 9.0 and a4-parameter logistics fit was used to define the dose-response curves.There were no constraints used for the 4-parameter logistic functionwhen plotting the data. Graphical reports were generated using thefollowing analysis: R2 (correlation coefficient), a (Max for data set),b (hillslope), and X0±SE (EC₅₀ value±standard error). The resultsindicated that EC₅₀ values of less than 2 pM could be achieved withcells differentiated for 48-72 hrs (FIG. 4). The finding thatdifferentiated cells could be used between 48 hrs to 72 hrs ofdifferentiation, with no significant changes on the performance of thecells, highlights the robustness of the assay. Although differentiationtime periods less than 48 hrs may not be suitable for picomolar testingof formulated product, these lesser differentiation times are sensitiveenough for bulk drug substance testing.

4. Optimization of BoNT/a Treatment Time.

To determine the optimal length of time cells form a cell line need tobe treated with a BoNT/A, various lengths of BoNT/A treatment times weretested. A suitable density of cells from a SiMa cell line was platedinto the wells of poly-D-lysine coated 96-well cell culture platescontaining 100 μL of a serum-free medium containing Minimum EssentialMedium, 2 mM GlutaMAX™ I with Earle's salts, 1×B27 supplement, 1×N2supplement, 0.1 mM Non-Essential Amino Acids, 10 mM HEPES and 25 μg/mLGT1b. Cells were plated and incubated in a 37° C. incubator under 5%carbon dioxide until the cells differentiated, as assessed by standardand routine morphological criteria, such as growth arrest and neuriteextension (approximately 3 days). The media was aspirated from each welland replaced with fresh media containing either 0 (untreated sample),0.1 pM, 0.2 pM, 0.4 pM, 0.8 pM, 1.6 pM, 3.1 pM, 6.3 pM, 12.5 pM, or 25pM of a BoNT/A complex in RPMI 1640 growth medium in triplicate togenerate a full dose-response. Five different BoNT/A treatment lengthregimens were performed: 1) a 6 hrs BoNT/A treatment, removal andwashing of cells, an incubation of cells for 18 hr without BoNT/A, andharvesting of cells as described above in Section 1; 2) a 24 hrs BoNT/Atreatment, removal and washing of cells, and harvesting of cells asdescribed above in Section 1; 3) a 24 hrs BoNT/A treatment, removal andwashing of cells, an incubation of cells for 24 hr without BoNT/A, andharvesting of cells as described above in Section 1; 4) a 24 hrs BoNT/Aincubation, removal and washing of cells, an incubation of cells for 48hr without BoNT/A, and harvesting of cells as described above in Section1; and 5) a 24 hrs BoNT/A incubation, removal and washing of cells, anincubation of cells for 72 hr without BoNT/A, and harvesting of cells asdescribed above in Section 1. After harvesting, the proteinconcentrations of cell lysates, detection of SNAP-25 cleavage product byECL sandwich ELISA performed, and the EC₅₀ calculated as describedabove. The results indicate that EC₅₀ values of less than 2 pM could beachieved with any of the BoNT/A treatments tested (FIG. 5).Interestingly, the 24 hrs+24 hrs, 24 hrs+48 hrs, and 24 hrs+73 hrsBoNT/A treatment regimes generated essentially the same EC₅₀ values, 1.0pM, 1.1, pM and 0.9 pM respectively. The EC₅₀ values generated for the 6hrs+18 hrs and 24 hrs+0 hrs BoNT/A treatment regimes were 1.7 pM and 1.6pM respectively. Although the amount of signal obtained was lower, theseresults indicate that BoNT/A treatment times between 6 hrs to 24 hrsplus one day to three days post-treatment incubation can be used togenerate an EC₅₀ that is adequate for detecting BoNT/A activity and giveflexibility in the assay's overall time course.

5. Sensitivity of Immuno-Based Method of Detecting BoNT/a Activity.

To evaluate the sensitivity of the immuno-based methods of detectingBoNT/A activity disclosed in the present specification, the timing ofBoNT/A uptake by cells susceptible to BoNT/A intoxication wasdetermined. A suitable density of cells from a SiMa cell line was platedinto the wells of poly-D-lysine coated 96-well cell culture platescontaining 100 μL of a serum-free medium containing Minimum EssentialMedium, 2 mM GlutaMAX™ I with Earle's salts, 1×B27 supplement, 1×N2supplement, 0.1 mM Non-Essential Amino Acids, 10 mM HEPES and 20 μg/mLGT1b. Cells were incubated in a 37° C. incubator under 5% carbon dioxideuntil the cells differentiated, as assessed by standard and routinemorphological criteria, such as growth arrest and neurite extension(approximately 3 days). The media was aspirated from each well, replacedwith fresh media containing 1 nM of a BoNT/A complex, and the BoNT/Atreated cells were incubated at six different time points of 0 min(neurotoxin added and then immediately removed), 5 min, 10 min, 20 min,30 min, and 60 min. A negative control of media with no BoNT/A (0 nM)was used. After incubation, the cells were washed and harvested asdescribed above in Section 1. After harvesting, the proteinconcentrations of cell lysates, detection of SNAP-25 cleavage product byECL sandwich ELISA performed, and the EC₅₀ calculated as describedabove. The results indicated that uptake of BoNT/A by the cells tookless than one minute before producing significant amounts of SNAP-25cleavage product over background (FIG. 6).

6. Specificity of Immuno-Based Method of Detecting BoNT/a Activity.

To evaluate the specificity of the immuno-based methods of detectingBoNT/A activity disclosed in the present specification, the capacity ofcells susceptible to BoNT/A intoxication to accurately distinguishBoNT/A to the exclusion of partially inactivated BoNT/A was determined.A suitable density of cells from a SiMa cell line was plated into thewells of poly-D-lysine coated 96-well cell culture plates containing 100μL of a serum-free medium containing Minimum Essential Medium, 2 mMGlutaMAX™ I with Earle's salts, 1×B27 supplement, 1×N2 supplement, 0.1mM Non-Essential Amino Acids, 10 mM HEPES and 25 μg/mL GT1b. Cells wereincubated in a 37° C. incubator under 5% carbon dioxide until the cellsdifferentiated, as assessed by standard and routine morphologicalcriteria, such as growth arrest and neurite extension (approximately 3days). The media was aspirated from each well and replaced with freshmedia containing either 1) 0 (untreated sample), 0.03 pM, 0.1 pM, 0.31pM, 0.93 pM, 2.78 pM, 8.33 pM, and 25 pM, of a BoNT/A complex; 2) 0,0.14 nM, 0.41 nM, 1.23 nM, 3.7 nM, 11.11 nM, 33.33 nM, and 100 nM of aninactive BoNT/A (iBoNT/A); or 3) 0, 0.14 nM, 0.41 nM, 1.23 nM, 3.7 nM,11.11 nM, 33.33 nM, and 100 nM of an LH_(N)/A fragment. The iBoNT/Acontains a mutation in the zinc binding domain of the light chain thatcompletely inactivates the metalloprotease activity of the neurotoxin,see, e.g., Liqing Zhou, et al., Expression and Purification of the LightChain of Botulinum Neurotoxin A: A Single Mutation Abolishes itsCleavage of SNAP-25 and Neurotoxicity after Reconstitution with theHeavy Chain, Biochemistry 34: 15175-15181 (1995), which is herebyincorporated by reference in its entirety. The LH_(N)/A fragment lacksthe binding domain, but contains an intact translocation domain andlight chain, see, e.g., Clifford C. Shone, et al., Recombinant ToxinFragments, U.S. Pat. No. 6,461,617, which is hereby incorporated byreference in its entirety. After 24 hrs treatment, the cells werewashed, incubated for an additional two days without toxin to allow forthe cleavage of SNAP-25 substrate, and harvested as described above inSection 1. After harvesting, the protein concentrations of cell lysates,detection of SNAP-25 cleavage product by ECL sandwich ELISA performed,and the EC₅₀ calculated as described above. The results indicate thatthe binding affinity of cells for iBoNT/A and LH_(N)/A (EC₅₀>100 nM) areat least 60,000 lower than the binding affinity for BoNT/A (EC₅₀=1.6 pM)(FIG. 7). No SNAP-25 cleavage product was detected in cells treated withiBoNT/A at all concentrations tested. Although a low amount of SNAP-25cleavage product was detected in cells treated with the highest dose ofthe LH_(N)/A fragment, this activity is due to non-specific uptake ofthis fragment due to the activity of the translocation domain. Thus, theresults indicate that the immuno-based methods of detecting BoNT/Aactivity disclosed in the present specification can measure all thesteps involved in the intoxication process whereby a BoNT/Aproteolytically cleaves a SNAP-25 substrate and encompasses the bindingof a BoNT/A to a BoNT/A receptor, the internalization of theneurotoxin/receptor complex, the translocation of the BoNT/A light chainfrom an intracellular vesicle into the cytoplasm and the proteolyticcleavage of a SNAP-25.

Example VI Immuno-Based Method of Detecting BoNT/a Activity Using ECLSandwich ELISA

The following example illustrates immuno-based methods of detectingBoNT/A activity by detecting a SNAP-25 cleavage product using aα-SNAP-25 monoclonal antibody specific for a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond using ECL sandwich ELISA.

To prepare a lysate from cells treated with a BoNT/A, a suitable densityof cells from an established cell line was plated into the wells of96-well tissue culture plates containing 100 μL of a serum-free mediumcontaining Minimum Essential Medium, 2 mM GlutaMAX™ I with Earle'ssalts, 1×B27 supplement, 1×N2 supplement, 0.1 mM Non-Essential AminoAcids, 10 mM HEPES and 25 μg/mL GT1b (see Examples I and II). Thesecells were incubated in a 37° C. incubator under 5% carbon dioxide untilthe cells differentiated, as assessed by standard and routinemorphological criteria, such as growth arrest and neurite extension(approximately 3 days). The media from the differentiated cells wasaspirated from each well and replaced with fresh media containing either0 (untreated sample), 0.03 pM, 0.1 pM, 0.3 pM, 0.9 pM, 2.8 pM, 8.3 pM,and 25 pM of a BoNT/A complex. After a 24 hr treatment, the cells werewashed, and incubated for an additional two days without toxin. To cellswere harvested as described in Example V.

To prepare the α-SNAP-25 capture antibody solution, the α-SNAP-25monoclonal antibody contained in the ascites from hybridoma cell line2E2A6 was purified using a standard Protein A purification protocol Toprepare the α-SNAP-25 detection antibody solution, α-SNAP-25 rabbitpolyclonal antibody S9684 (Sigma, St. Louis, Mo.) was conjugated toRuthenium(II)-tris-bipyridine-(4-methysulfonate) NHS ester labelingreagent (Meso Scale Discovery, Gaithersburg, Md.) according to themanufacturer's instructions (Meso Scale Discovery, Gaithersburg, Md.).The conjugation reaction, purification of labeled α-SNAP-25 antibody,concentration determination and storage were as described in Example V.

To prepare the solid phase support comprising the capture antibody thatis specific for a SNAP-25 cleaved product, approximately 5 μL ofα-SNAP-25 monoclonal antibody 2E2A6 solution (20 μg/mL in 1×PBS) wasadded to each well of a 96-well MSD High Bind plate and the solution isallowed to air dry in a biological safety cabinet for 2-3 hours in orderto liquid evaporate the solution. The capture antibody-bound wells werethen blocked and used directly to detect BoNT/A activity.

To detect the presence of a cleaved SNAP-25 product by ECL sandwichELISA analysis, the Blocking Buffer from stored plates was aspiratedfrom the wells, 25 μL of a lysate from cells treated with BoNT/A wasadded to each well and the plates were incubated at 4° C. for overnight.Plate wells were washed three times by aspirating the cell lysate andrinsing each well three times with 200 μL 1×PBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). After washing, 25 μl of 5μg/mL detection antibody solution comprising 2% Amersham BlockingReagent in 1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate) was added to each well, the plate was sealed, and thesealed plate was incubated at room temperature at room temperature for 1hour with shaking. After detection antibody incubation, the wells werewashed three times with 200 μL 1×PBS, 0.1% TWEEN-20® (polyoxyethylene(20) sorbitan monolaureate). After washing 150 μL of 1×Read Buffer (MesoScale Discovery, Gaithersburg, Md.) was added to each well and theplates were read using a SECTOR™ Imager 6000 Image Reader (Meso ScaleDiscovery, Gaithersburg, Md.). The collected data was analyzed and theEC₅₀ calculated as described in Example V. A representative result isshown in FIG. 8. These results indicated that on average 1.0 pM ofBoNT/A at the EC₅₀ was detected (a range of about 0.3 pM to about 2.0pM) with a signal-to-noise ratio for the lower asymptote of about 15:1to about 20:1 and a signal-to-noise ratio for the upper asymptote ofabout 20:1 to about 500:1.

Example VII Immuno-Based Method of Detecting BoNT/a Activity Using CLSandwich ELISA

The following example illustrates immuno-based methods of detectingBoNT/A activity by detecting a SNAP-25 cleavage product using aα-SNAP-25 monoclonal antibody specific for a SNAP-25 having acarboxyl-terminus at the P₁ residue of the BoNT/A cleavage site scissilebond by CL sandwich ELISA.

Lysate from cells treated with a BoNT/A and the α-SNAP-25 captureantibody solution were prepared as described in Example VI.

To prepare the α-SNAP-25 detection antibody solution, α-SNAP-25polyclonal antibody S9684 (Sigma, St. Louis, Mo.) was conjugated toHorseradish peroxidase (HRP) according to the manufacturer'sinstructions (Pierce Biotechnology, Inc., Rockford, Ill.). Theconjugation reaction was performed by adding to 500 μL of 1 mg/mLα-SNAP-25 polyclonal antibodies to a vial containing lyophilizedactivated peroxidase, mixing the components, and then adding 10 μL ofsodium cyanoborohydride. This reaction mixture was incubated at roomtemperature for 1 hour in a fume hood. After quenching the reaction, thelabeled antibodies were purified using a standard spin column protocoland the protein concentration determined using a standard colorimetricprotein assay. The absorbance of the α-SNAP-25 polyclonal antibody/HRPconjugate was measured at 455 nm using a spectrophotometer to determinethe concentration in moles per liter. The α-SNAP-25 detection antibodysolution was stored at 4° C. until needed.

To prepare the solid phase support comprising the α-SNAP-25 captureantibody that is specific for the SNAP-25 cleaved product, approximately100 μL of α-SNAP-25 monoclonal antibody 2E2A6 solution (1 mg/mL in1×PBS) was added to each well of a 96-well Greiner white plate and theplates were incubated at 4° C. overnight, and then any excess antibodysolution was discarded. The capture antibody-bound wells were thenblocked by adding 150 μl of Blocking Buffer comprising 2% AmershamBlocking Reagent (GE Life Sciences, Piscataway, N.J.) and 10% goat serum(VWR, West Chester, Pa.) at room temperature for 1 hour. The blockingbuffer was discarded and the plates were blotted dry on paper towels byinverting and tapping. The capture antibody-bound wells were thenblocked and used directly to detect BoNT/A activity.

To detect the presence of a cleaved SNAP-25 product by CL sandwich ELISAanalysis, 50 μL of a lysate from cells treated with BoNT/A was added toeach well, the plate was sealed, and the sealed plate was incubated on ashaker rotating at 500 rpm at 4° C. for 2-4 hours to overnight. Platewells were washed three times by aspirating the cell lysate and rinsingeach well three times with 200 μl 1×PBS, 0.05% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). After washing, 100 μL of 1mg/mL α-SNAP-25 polyclonal antibody/HRP detection antibody solutioncomprising 2% Amersham Blocking Reagent in 1×PBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate) was added to each well, theplate was sealed, and the sealed plate was incubated on a shakerrotating at 650 rpm at room temperature for 1 hour. After detectionantibody incubation, the wells were washed three times with 200 μl1×PBS, 0.05% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate).After washing 100 μl of SuperSignal ELISA Pico 1:1 mixture (PierceBiotechnology, Inc., Rockford, Ill.) was added to each well and theplates were read using a luminometer (Molecular Devices, Sunnyvale,Calif.) at 395 nm. The collected data was analyzed and the EC₅₀calculated as described in Example V. These results indicated that onaverage 1.0 pM of BoNT/A at the EC₅₀ was detected (a range of about 0.3pM to about 2.0 pM) with a signal-to-noise ratio for the lower asymptoteof about 15:1 to about 20:1 and a signal-to-noise ratio for the upperasymptote of about 20:1 to about 500:1.

Example VIII Immuno-Based Method of Detecting BoNT/a Activity UsingMultiplex ECL Sandwich ELISA

The following example illustrates multiplex immuno-based methods ofdetecting BoNT/A activity by detecting a SNAP-25 cleavage product usinga α-SNAP-25 monoclonal antibody specific for a SNAP-25 cleavage productand a second antibody pair for a different protein.

1. Preparation and Identification of Capture Antibody-Detection AntibodyPair for a Second Protein.

To obtain an untreated cell lysate for analysis, a suitable density ofcells from a stock culture of SiMa cells were seeded into a T175 flaskcontaining 40 mL of a growth medium containing 1×RPMI 1640, 10% FBS, 0.1mM Non-Essential Amino Acids, 10 mM HEPES, 1 mM sodium pyruvate, and 100U/100 μg of pennicillin-streptomycin. These cells were incubated in a37° C. incubator under 5% carbon dioxide until the cells wereapproximately 70-90% confluent. The cells were washed and harvested bylysing in freshly prepared Triton X-100 Lysis Buffer (20 mM Tris pH 7.5,150 mM sodium chloride, 0.001M EDTA, 1 mM EGTA, and 1% Triton-X-100) at4° C. for approximately 30 minutes with constant agitation. Lysed cellswere centrifuged at approximately 3300-3330×g for 40 minutes at 8° C. toeliminate debris using a bench-top centrifuge.

To identify an appropriate capture antibody-detection antibody pair fora second protein, an ECL sandwich ELISA analysis was conducted on 21different combinations of capture and detection antibody pairscomprising of five different proteins (Table 13). The antibodies usedwere α-Syntaxin 1A-HPC mouse monoclonal antibody S0664 (Sigma, St.Louis, Mo.), α-GAPDH mouse monoclonal antibody MAB374 (Chemicon,Temecula, Calif.), α-Syntaxin 1 rabbit polyclonal antibody S1172-1(Sigma, St. Louis, Mo.), α-GAPDH rabbit polyclonal antibody 2275-PC-1 (R& D Systems, Minneapolis, Minn.), α-Syntaxin 2 rabbit polyclonalantibody S5687 (Sigma, St. Louis, Mo.), α-human syntaxin 2 mousemonoclonal antibody MAB2936 (R & D Systems, Minneapolis, Minn.), α-mousesyntaxin 2 goat polyclonal antibody AF2568 (Sigma, St. Louis, Mo.),α-Syntaxin 2 rabbit polyclonal antibody AB5596 (Sigma, St. Louis, Mo.),α-Syntaxin 1 rabbit polyclonal antibody S1172-2 (Sigma, St. Louis, Mo.),a-h, m, r actin sheep polyclonal antibody AF4000 (R & D Systems,Minneapolis, Minn.), α-beta actin mouse monoclonal antibody A1978(Sigma, St. Louis, Mo.), α-beta mouse polyclonal antibody actin A2228(Sigma, St. Louis, Mo.), mouse α-GAPDH mouse monoclonal antibody G8795(Sigma, St. Louis, Mo.), α-GAPDH rabbit polyclonal antibody G9595(Sigma, St. Louis, Mo.).

To prepare the second protein capture antibody solution, the monoclonalantibodies were purchased as purified antibodies. To prepare the secondprotein detection antibody solution, the appropriate antibody wasconjugated to Ruthenium(II)-tris-bipyridine-(4-methysulfonate) NHS esterlabeling reagent (Meso Scale Discovery, Gaithersburg, Md.) according tothe manufacturer's instructions (Meso Scale Discovery, Gaithersburg,Md.). The conjugation reaction was performed by adding 30 μL ofdistilled water reconstituted MSD SULFO-TAG™ stock solution to 200 μL of2 mg/mL polyclonal antibodies and incubating the reaction at roomtemperature for 2 hours in the dark. The labeled antibodies werepurified using a standard spin column protocol and the proteinconcentration determined using a standard colorimetric protein assay.The absorbance of the antibody/MSD SULFO-TAG™ conjugate was measured at455 nm using a spectrophotometer to determine the concentration in molesper liter. The detection antibody solution was stored at 4° C. untilneeded.

To prepare the solid phase support comprising the capture antibody thatis specific for a SNAP-25 cleaved product, approximately 5 μL ofα-SNAP-25 monoclonal antibody 2E2A6 solution (20 μg/mL in 1×PBS) wasadded to each well of a 96-well MSD High Bind plate and the solution isallowed to air dry in a biological safety cabinet for 2-3 hours in orderto liquid evaporate the solution, and then the plates were sealed andstored at 4° C. until needed. The dried capture antibody-bound wellswere then blocked by adding 150 μL of Blocking Buffer comprising of 3%BSA (Pierce, Rockford, Ill.) 10% goat serum (Rockland Immunochemicals,Gilbertsville, Pa.), and Difco 1% skim milk (BD BioSciences FranklinLakes, N.J.) in 0.05% Tween-20 PBS at room temperature for 1-2 hours.

To detect the presence of protein by ECL sandwich ELISA analysis, theBlocking Buffer from stored plates was aspirated from the wells, 25 μLof a lysate from cells treated with BoNT/A, as described above, wasadded to each well and the plates were incubated at 4° C. for overnight.Plate wells were washed three times by aspirating the cell lysate andrinsing each well three times with 200 μL 1×PBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). After washing, 25 μL of 5μg/mL the appropriate second protein detection antibody solution,resuspended in the blocking buffer as described above, was added to eachwell, the plate was sealed, and the sealed plate was incubated at roomtemperature for about 1 hour with shaking. After detection antibodyincubation, the wells were washed three times with 250 μL 1×PBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate). After washing150 μL of 1× Read Buffer (Meso Scale Discovery, Gaithersburg, Md.) wasadded to each well and the plates were read using a SECTOR™ Imager 6000Image Reader (Meso Scale Discovery, Gaithersburg, Md.). A ratio wascalculated by dividing the signal obtained from the untreated celllysates for each antibody-pair by the signal obtained for the lysisbuffer control (0 nM dose) for each antibody-pair (Table 13). Theseresults indicated that among the twenty-one different combinations ofantibody pairs tested, only two antibody pairs had signal-to-noiseratios above 10:1 for the higher dose tested: Pair No. 16 α-GAPDH mousemonoclonal antibody MAB374 and α-GAPDH rabbit polyclonal antibodyRDS2275-PC-1; and Pair 21: α-GAPDH mouse monoclonal antibody MAB374 andα-GAPDH rabbit polyclonal antibody G9545. The α-GAPDH mouse monoclonalantibody MAB374 and α-GAPDH rabbit polyclonal antibody G9545 pair wasselected as the second protein capture antibody-detection antibody pairfor the multiplex ECL sandwich ELISA.

TABLE 13 Screening of Second Protein Antibody Combinations Signal/NoiseAntibody Detection Ratio Pair No. Capture Antibody Detection Antibody ofProtein (lysate/buffer) 1 α-syntaxin 2 S5687 pAb α-syntaxin 2 MAB2936 No0.92 mAb 2 α-syntaxin 2 AF2568 pAb α-syntaxin 2 AB5596 pAb No 1.1 3α-syntaxin 2 AF2568 α-syntaxin 2 S5687 pAb No 1.11 4 α-syntaxin 2 AF2936pAb α-syntaxin 2 AB5596 pAb Yes 1.63 5 α-syntaxin 2 AF2936 pAbα-syntaxin 2 S5687 pAb Yes 1.6 6 α-syntaxin 2 AB5596 pAb α-syntaxin 2S5687 pAb No 0.82 7 α-syntaxin 2 AB5596 pAb α-syntaxin 2 MAB2936 No 0.87mAb 8 α-syntaxin 2 MAB2936 α-syntaxin 2 AB5596 pAb Yes 1.2 mAb 9α-syntaxin 2 MAB2936 α-syntaxin 2 S5687 pAb No 1.07 mAb 10 α-syntaxinS0664 mAb α-syntaxin 1 S1172-1 pAb Yes 4.23 11 α-syntaxin S0664 mAbα-syntaxin 1 S1172-2 pAb No 1.21 12 α-syntaxin 1 S1172-1 pAb α-syntaxinS0664 mAb Yes 5.5 13 α-syntaxin 1 S1172-2 pAb α-syntaxin S0664 mAb Yes2.5 14 α-h,m,r actin AF4000 pAb α-beta actin A 1978 mAb No 1.04 15α-h,m,r actin AF4000 pAb α-beta actin A2228 mAb No 1.08 16 α-GAPDHMAB374 mAb α-GAPDH 2275-PC-1 pAb Yes 20.04 17 α-GAPDH MAB374 mAb α-GAPDHG8795 mAb No 0.89 18 α-GAPDH 2275-PC-1 pAb α-GAPDH MAB374 mAb No 1.08 19α-GAPDH 2275-PC-1 pAb α-GAPDH G8795 mAb Yes 1.27 20 α-GAPDH G8795 mAbα-GAPDH 2275-PC-1 pAb Yes 2.74 21 α-GAPDH MAB374 mAb α-GAPDH G9545 pAbYes ≥100

2. Immuno-Based Method of Detecting BoNT/a Activity Using Multiplex ECLSandwich ELISA.

To obtain a BoNT/A treated cell lysate for analysis, a suitable densityof cells from a stock culture of a SiMa cell line were seeded into apoly-D-lysine 96-well plate containing a serum-free medium containingMinimum Essential Medium, 2 mM GlutaMAX™ I with Earle's salts, 1×B27supplement, 1×N2 supplement, 0.1 mM Non-Essential Amino Acids, 10 mMHEPES. These cells were incubated in a 37° C. incubator under 5% carbondioxide until the cells differentiated, as assessed by standard androutine morphological criteria, such as growth arrest and neuriteextension (approximately 3 days). The media was aspirated from each welland replaced with fresh media containing either 0 (untreated sample),0.67 U/mL, 2.35 U/mL, 8.23 U/mL, 28.82 U/mL, 101 U/mL, 353 U/mL of aBoNT/A complex. After a 24 hr treatment, the cells were washed,incubated for an additional two days without toxin. The cells werewashed, harvested, and processed as described above in Section 1.

The α-SNAP-25 capture antibody solution and the α-SNAP-25 detectionantibody solution, were prepared as described in Example VII. To preparethe α-GAPDH capture antibody solution, the α-GAPDH monoclonal antibodymouse MAB374 (Chemicon, Temecula, Calif.) was prepared as described inSection 1 above. To prepare the α-GAPDH detection antibody solution,α-GAPDH rabbit polyclonal antibody G9545 (Sigma, St. Louis, Mo.) wasconjugated to Ruthenium(II)-tris-bipyridine-(4-methysulfonate) NHS esterlabeling reagent (Meso Scale Discovery, Gaithersburg, Md.) according tothe manufacturer's instructions (Meso Scale Discovery, Gaithersburg,Md.). The conjugation reaction, purification of labeled α-SNAP-25antibody, concentration determination and storage were as described inSection 1 above.

To prepare the solid phase support comprising the α-SNAP-25 captureantibody and the α-GAPDH capture antibody, approximately 2.5 nL of theα-SNAP-25 capture antibody solution (45 μg/mL in 1×PBS) and 2.5 nL ofthe α-GAPDH capture antibody solution (120 pg/mL in 1×PBS) were added toeach well of a 96-well MSD High Bind plate in a muliplex format using arobotic system. The solution is allowed to air dry in a biologicalsafety cabinet for at least 2-3 hours in order to liquid evaporate thesolution. The capture antibody-bound wells were then blocked and useddirectly to detect BoNT/A activity and the GAPDH protein.

To detect the presence of SNAP-25 cleavage product by multiplex ECLsandwich ELISA analysis, the Blocking Buffer from stored plates wasaspirated from the wells, 25 μL of a lysate from cells treated withBoNT/A, as described above, was added to each well and the plates wereincubated at 4° C. for overnight. Plate wells were washed three times byaspirating the cell lysate and rinsing each well three times with 200 μL1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate).After washing, 25 μL of 5 μg/mL the α-SNAP-25 detection antibodysolution and 25 μL of 5 μg/mL the α-GAPDH detection antibody solution,as described above, was added to each well, the plate was sealed, andthe sealed plate was incubated at room temperature for about 1 hour withshaking. After detection antibody incubation, the wells were washedthree times with 250 μL 1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20)sorbitan monolaureate). After washing 150 μL of 1×Read Buffer (MesoScale Discovery, Gaithersburg, Md.) was added to each well and theplates were read using a SECTOR™ Imager 6000 Image Reader (Meso ScaleDiscovery, Gaithersburg, Md.). The collected data was analyzed and therelative potency from the normalized data is calculated as described inExample V, except that PLA 2.0 software (Stegmann Systems, GmbH,Germany) was used.

As a comparison, the detection of SNAP-25 cleavage product was alsoperformed using the singleplex ECL sandwich ELISA as described inExample VI.

The results indicated that the SNAP-25 data obtained from the singleplexECL sandwich ELISA, or from the non-normalized SNAP-25 data obtainedfrom the multiplex ECL sandwich ELISA, revealed one outlier sample dosethat did not fit into the dose-response curve. However, normalization ofthe SNAP-25 data against the GAPDH data gave a better curve fit and thepotency was closer to the expected value.

Example IX Immuno-Based Method of Detecting BoNT/a Activity UsingMultiplex EC Sandwich ELISA

The following example illustrates multiplex immuno-based methods ofdetecting BoNT/A activity by detecting a SNAP-25 cleavage product usinga α-SNAP-25 monoclonal antibody specific for a SNAP-25 cleavage productand a second antibody pair for a different protein.

The lysate from cells treated with a BoNT/A was prepared as described inExample VI. The α-SNAP-25 capture antibody solution, the α-SNAP-25detection antibody solution, and the α-SNAP-25 solid phase support wereprepared as described in Example VII.

To prepare α-GAPDH capture antibody solution, α-GAPDH monoclonalantibody MAB374 (Millipore, Billerica, Mass.) was purchased as apurified antibody. To prepare the α-GAPDH detection antibody solution,an α-GAPDH polyclonal antibody G9545 (Sigma, St. Louis, Mo.) wasconjugated to Horseradish peroxidase (HRP) according to themanufacturer's instructions (Pierce Biotechnology, Inc., Rockford,Ill.). The conjugation reaction, concentration determination and storagewere as described in Example VII.

To prepare the solid phase support comprising a second capture antibodyspecific for the second protein, approximately 100 μL of monoclonalantibody solution comprising 1 μg/mL α-GAPDH monoclonal antibody MAB374was added to each well of a 96-well Greiner white plate and the plateswere incubated at 4° C. overnight, and then any excess antibody solutionwas discarded. The α-GAPDH capture antibody-bound wells were thenblocked by adding 150 μl of Blocking Buffer comprising 2% AmershamBlocking Reagent (GE Life Sciences, Piscataway, N.J.) and 10% goat serum(VWR, West Chester, Pa.) at room temperature for 1 hour. The blockingbuffer was discarded and the plates were blotted dry on paper towels byinverting and tapping. The capture antibody-bound wells were thenblocked and used directly to detect BoNT/A activity.

To detect the presence of a cleaved SNAP-25 product by multiplex CLsandwich ELISA analysis, 50 μL of cell lysates from cells treated withBoNT/A was added to each well of the α-SNAP-25 capture antibody solidphase support and the α-GAPDH capture antibody solid phase support, theplate was sealed, and the sealed plate was incubated on a shakerrotating at 500 rpm at 4° C. for 2-4 hours to overnight. Plate wellswere washed three times by aspirating the cell lysate and rinsing eachwell three times with 200 μl 1×PBS, 0.05% TWEEN-20® (polyoxyethylene(20) sorbitan monolaureate). After washing, 100 μL of a detectionantibody solution comprising 2% Amersham Blocking Reagent in 1×PBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate), and 1 mg/mLα-SNAP-25 polyclonal antibody/HRP was added to each well of theα-SNAP-25 capture antibody solid phase support, the plate was sealed,and the sealed plate was incubated on a shaker rotating at 650 rpm atroom temperature for 1 hour. Similarly, 100 μL of a detection antibodysolution comprising 2% Amersham Blocking Reagent in 1×PBS, 0.1%TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate), and 0.25 mg/mLα-GAPDH G9545 polyclonal antibody/HRP (Sigma Co., St Louis, Mo.) wasadded to each well of the α-GAPDH capture antibody solid phase support,the plate was sealed, and the sealed plate was placed on a shakerrotating at 650 rpm at room temperature for 1 hour. After detectionantibody incubation, the wells were washed three times with 200 μl1×PBS, 0.05% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate).After washing 100 μl of SuperSignal ELISA Pico 1:1 mixture (PierceBiotechnology, Inc., Rockford, Ill.) was added to each well and theplates were read using a luminometer (Molecular Devices, Sunnyvale,Calif.) at 395 nm. The collected data was analyzed and the EC₅₀calculated as described in Example V. The results indicated that thedata points collected for the amounts of α-SNAP-25 antibody-antigencomplex detected were a better fit after normalization to the amounts ofα-GAPDH antibody-antigen complex detected, thereby producing a moreaccurate reading. These results indicated that on average 1.0 pM ofBoNT/A at the EC₅₀ was detected (a range of about 0.3 pM to about 2.0pM) with a signal-to-noise ratio for the lower asymptote of about 15:1to about 20:1 and a signal-to-noise ratio for the upper asymptote ofabout 20:1 to about 500:1.

A similar design can be used for multiplex immuno-based methods ofdetecting BoNT/A activity by detecting a SNAP-25 cleavage product usinga α-SNAP-25 monoclonal antibody specific for a SNAP-25 cleavage producthaving a carboxyl-terminus at the P₁ residue of the BoNT/A cleavage sitescissile bond using ECL sandwich ELISA with the same α-GAPDH antibodypair.

Example X Immuno-Based Method to Detect Picomolar Amounts of BoNT/A

The following example illustrates how to perform immuno-based methods ofdetecting BoNT/A activity that can detect picomolar amounts of theBoNT/A pharmaceutical product, such as, e.g., BOTOX® DYSPORT®/RELOXIN®,PURTOX®, XEOMIN®, NEURONOX®, or BTX-A.

1. Immuno-Based Method of Detecting BoNT/a Using ECL Sandwich ELISA.

To prepare a lysate from cells treated with a BoNT/A, approximately50,000 to 150,000 cells from an established cell line were plated intothe wells of 96-well tissue culture poly-D-lysine plates containing 100μL of a serum-free medium containing Minimum Essential Medium, 2 mMGlutaMAX™ I with Earle's salts, 1×B27 supplement, 1×N2 supplement, 0.1mM Non-Essential Amino Acids, 10 mM HEPES and 25 μg/mL GT1b (seeExamples I and II). These cells were incubated in a 37° C. incubatorunder 5% carbon dioxide until the cells differentiated, as assessed bystandard and routine morphological criteria, such as growth arrest andneurite extension (approximately 2 to 3 days). The media from thedifferentiated cells was aspirated from each well and replaced withfresh media containing either 0 (untreated sample), 0.03 pM, 0.1 pM, 0.3pM, 0.9 pM, 2.8 pM, 8.3 pM, or 25 pM of a BoNT/A pharmaceutical productreconstituted in a sodium chloride free solution; or 0 (untreatedsample), 0.7 U/mL, 2.1 U/mL, 6.2 U/mL, 18.5 U/mL, 55.6 U/mL, 166.7 U/mLor 500 U/mL of a BoNT/A pharmaceutical product reconstituted in a sodiumchloride free medium. Because the BoNT/A pharmaceutical product containssodium chloride, its addition to the culture medium resulted in ahypertonic media that was detrimental to cell viability. To circumventthe hypertonicity issue, 200 μL of MEM media made without sodiumchloride was used to reconstitute the BoNT/A pharmaceutical productgiving a final concentration of 25 pM BoNT/A (500 U/mL). The matrix waskept constant for all concentrations along the dose-response curve byadding sodium chloride in the media used to make the dilutions match theamount of excipients present at the highest concentration used (25 pM or500 U/mL). After a 24 hr treatment, the cells were washed, and incubatedfor an additional two days without toxin. To harvest the cells, themedium was aspirated, washed with 1×PBS, and lysed by adding 30 μl ofLysis Buffer comprising 50 mM HEPES, 150 mM NaCl, 1.5 mM MgCl₂, 1 mMEGTA, 1% Triton X-100 to each well, and the plate incubated on a shakerrotating at 500 rpm for 30 minutes at 4° C. The plate was centrifuged at4000 rpm for 20 minutes at 4° C. to pellet cellular debris and thesupernatant was transferred to a capture antibody coated 96-well plateto perform the detection step.

The α-SNAP-25 capture antibody solution, the α-SNAP-25 detectionantibody solution, and the solid phase support comprising the captureantibody that is specific for a SNAP-25 cleaved product were prepared asdescribed in Example VI.

To detect the presence of a cleaved SNAP-25 product by ECL sandwichELISA analysis, the Blocking Buffer from stored plates was aspirated, 25μL of a lysate from cells treated with BoNT/A was added to each well andthe plates were incubated at 4° C. for either 2 hrs or 24 hrs. Platewells were washed three times by aspirating the cell lysate and rinsingeach well three times with 200 μL 1×PBS, 0.1% TWEEN-20® (polyoxyethylene(20) sorbitan monolaureate). After washing, 25 μl of 5 μg/mL α-SNAP-25detection antibody solution comprising 2% Amersham Blocking Reagent in1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate) wasadded to each well, the plate was sealed, and the sealed plate wasincubated at room temperature for 1 hour with shaking. After α-SNAP-25detection antibody incubation, the wells were washed three times with200 μL 1×PBS, 0.1% TWEEN-20® (polyoxyethylene (20) sorbitanmonolaureate). After washing, the plates were processed, collected datawas analyzed, and the EO₅₀ calculated as described in Example V. Theseresults indicated that on average 1.0 pM of BoNT/A at the EC₅₀ wasdetected (a range of about 0.3 pM to about 2.0 pM) with asignal-to-noise ratio for the lower asymptote of about 15:1 to about20:1 and a signal-to-noise ratio for the upper asymptote of about 20:1to about 500:1 (FIG. 9). This method can also be performed in amultiplex fashion as described in Example VIII.

2. Immuno-Based Method of Detecting BoNT/a Using CL Sandwich ELISA.

Lysate from cells treated with a BoNT/A and the α-SNAP-25 captureantibody solution will be prepared as described in Example VI. Theα-SNAP-25 detection antibody solution and solid phase support comprisingthe capture antibody that is specific for a SNAP-25 cleaved product willbe prepared as described in Example VII.

To detect the presence of a cleaved SNAP-25 product by CL sandwich ELISAanalysis, 25 μL of a lysate from cells treated with BoNT/A will be addedto each well, the plate was sealed, and the sealed plate was incubatedon a shaker rotating at 500 rpm at 4° C. for either 2 hrs or 24 hrs.Plate wells will be washed three times by aspirating the cell lysate andrinsing each well three times with 200 μl 1×PBS, 0.05% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate). After washing, 100 μL of 1mg/mL α-SNAP-25 polyclonal antibody/HRP detection antibody solutioncomprising 2% Amersham Blocking Reagent in 1×PBS, 0.1% TWEEN-20®(polyoxyethylene (20) sorbitan monolaureate) will be added to each well,the plate was sealed, and the sealed plate was incubated on a shakerrotating at 650 rpm at room temperature for 1 hour. After detectionantibody incubation, the wells will be washed three times with 200 μl1×PBS, 0.05% TWEEN-20® (polyoxyethylene (20) sorbitan monolaureate).After washing 100 μl of SuperSignal ELISA Pico 1:1 mixture (PierceBiotechnology, Inc., Rockford, Ill.) will be added to each well and theplates will be read using a luminometer (Molecular Devices, Sunnyvale,Calif.) at 395 nm. The collected data will be analyzed and the EC₅₀ willbe calculated as described in Example V. This method can also beperformed in a multiplex fashion as described in Example VIII.

Example XI Immuno-Based Method to Detect Neutralizing α-BoNT/aAntibodies

The following example illustrates how to perform an immuno-based methodthat can detect the presence of neutralizing α-BoNT/A antibodies.

BoNT/A, is currently used for a wide range of medical indicationsincluding muscle hyperactivity, ophthalmologic, gastrointestinal,urologic, and cosmetic. With repeated long-term treatment of BoNT/A, apatient may develop neutralizing α-BoNT/A antibodies to the toxinleading to immunoresistance. Neutralizing α-BoNT/A antibodies inhibitBoNT/A activity by stopping the toxin's uptake into neuronal cells bybinding to the binding domain (H_(C)) and/or the translocation domain(H_(N)) of BoNT/A. Some studies have suggested that up to 5-10% ofpatients repeatedly treated for dystonia with formulations of BoNT/Ahave immunoresistance due to the development of neutralizing α-BoNT/Aantibodies. The established assay to determine the presence of theneutralizing α-BoNT/A antibodies in patient's blood is the mouseprotection assay (MPA). Currently, BoNT/A is incubated with a patient'sserum prior to injection into mice. The presence of antibodies ismanifested by a decreased response to the neurotoxin in the animal.Since the MPA is an in vivo based assay, it would be more cost and timeefficient if it was replaced with a cell-based assay.

To detect the presence or absence of neutralizing α-BoNT/A antibodies,the immuno-based methods of determining BoNT/A activity disclosed in thepresent specification can be used. One way is to determine the amount ofSNAP-25 cleavage product present after treatment with variousconcentrations of BoNT/A using a Western blot detection method, theother way was to use an ECL sandwich ELISA detection method.

To prepare a sample comprising neutralizing α-BoNT/A antibodies and anegative control sample known to lack α-BoNT/A neutralizing antibodies,serum was isolated from blood of different individuals. Individualsdeclining immunizations were referred to as naïve individuals.Individuals accepting immunization were referred to as immunizedindividuals. The blood was drawn into a serum tube with a clot activator(BD Biosciences, Bedford, Mass.). Serum was obtained by centrifugationof the blood at 1000×g for 10 minutes at 4° C. The serum of two donorswas obtained: one individual was immunized to BoNT/A while the other wasnot.

To prepare a lysate from cells treated with a sample comprising BoNT/A,SiMa cells were seeded in a poly-D-lysine 96-well plate anddifferentiated as described in Example VI. The human serums wereserially diluted 1:100-1:152,000 by 2.5 fold increments using serum-freemedia. The BoNT/A was suspended in 0.5 mL SiMa culture media at aconcentration of 10 pM. The media containing BoNT/A and α-BoNT/Aantibodies were mixed and incubated for 15 min or 1 hr at roomtemperature. The cells were treated with BoNT/A with human serum for 2hr followed by a 15 hr incubation in fresh growth media. The cells werealso treated for 15 hr with no additional incubation time.

To detect the presence of a cleaved SNAP-25 product by Western blotanalysis, the media was aspirated from each well, the cells suspended in50 μL of SDS-PAGE loading buffer, and then heated to 95° C. for 5minutes. An aliquot from each harvested sample was analyzed by Westernblot as described in Example I, except that harvested samples areseparated by SDS-PAGE using 12% 26-well Criterion gels (Bio-RadLaboratories, Hercules, Calif.), and the rabbit polyclonal α-SNAP-25₁₉₇antibody serum was used as the primary antibody (see Example IV). Theresults indicate that test samples resulted in reduced cleavage ofSNAP25 when compared to the negative control sample, demonstrating thatthe serum from the immunized individual contained neutralizing α-BoNT/Aantibodies.

To detect the presence of a cleaved SNAP-25 product by ECL SandwichELISA, the media was removed from each well and the cells were lysed asdescribed in Example V. The α-SNAP-25 capture antibody solution, theα-SNAP-25 detection antibody solution, and the α-SNAP-25 solid phasesupport were prepared as described in Example VII. Supernatants weretransferred to the α-SNAP-25 solid phase support and an ECL sandwichELISA assay was performed as detailed in Example V. The collected datawas analyzed and the EC₅₉ calculated as described in Example V, exceptthat the EC₅₀ is the serum dilution needed to inhibit the activity ofthe BoNT/A to ½ its maximum and the ratio of maximal signal(Signal_(Max)) to minimum signal (Signal_(Min)) was obtained by dividingthe SNAP-25 cleavage product signal obtained with the highest dilutionof serum by the signal obtained with the lowest serum dilution.

The results indicate that the presence of neutralizing α-BoNT/A in humanserum could be detected. The activity of the BoNT/A complex incubated inserum from the immunized individual decreased as the serum dilutiondecreased, whereas, the presence of naïve serum had no impact on theassay at every dilution tested. This assay can be performed using aformulated BoNT/A pharmaceutical product, a bulk BoNT/A complex, or apurified neurotoxin.

Example XII Immuno-Based Method to Detect BoNT/a Activity UsingEngineered Cells

The following example illustrates how to introduce a polynucleotidemolecule encoding a BoNT/A receptor into cells from an established cellline to further improve susceptibility to BoNT/A intoxication or improveBoNT/A uptake capacity.

To introduce an exogenous BoNT/A receptor into cells comprising anestablished cell line, an expression construct comprising apolynucleotide molecule of SEQ ID NO: 130 encoding the FGFR2 of SEQ IDNO: 59, or a polynucleotide molecule of SEQ ID NO: 139 encoding theFGFR3 of SEQ ID NO: 25, was transfected into cells from an establishedcell line by a cationic lipid method. A suitable density (about 5×10⁶cells) of cells from an established cell line are plated in a 100 mmtissue culture dish containing 5 mL of complete culture media and grownin a 37° C. incubator under 5% carbon dioxide until the cells reached adensity appropriate for transfection. A 3 mL transfection solution isprepared by adding 1.5 mL of OPTI-MEM Reduced Serum Medium containing 60μL of LipofectAmine 2000 (Invitrogen, Carlsbad, Calif.) incubated atroom temperature for 5 minutes to 1.5 mL of OPTI-MEM Reduced SerumMedium containing 24 pg of an expression construct encoding a FGFR2 or aFGFR3, or a control expression construct encoding a green fluorescentprotein (GFP). This transfection mixture was incubated at roomtemperature for approximately 30 minutes. The complete media is replacedwith the 3 mL transfection solution and the cells are incubated in a 37°C. incubator under 5% carbon dioxide for approximately 8 hours.Transfection media is replaced with 3 mL of fresh complete culture mediaand the cells are incubated in a 37° C. incubator under 5% carbondioxide for approximately 24 hours. Media is replaced with 3 mL of freshcomplete culture media containing approximately 1 mM G418 (Invitrogen,Carlsbad, Calif.). Cells are incubated in a 37° C. incubator under 5%carbon dioxide for approximately 1 week, the old media is replaced withfresh complete culture media containing 0.5 mM G418. Onceantibiotic-resistant colonies are established, resistant clones arereplated to new 100 mm culture plates containing fresh complete culturemedia, supplemented with approximately 0.5 mM G418 until these cellsreached a density of 6 to 20×10⁵ cells/mL.

To determine if the overexpression of BoNT/A receptors improved cellsusceptibility to BoNT/A intoxication or improved BoNT/A uptakecapacity, a dose-response curve was generated using cells treated withdifferent doses of a BoNT/A complex. To prepare a lysate from cellstreated with a BoNT/A, a suitable density of cells from an establishedtransfected cell line was plated into the wells of 96-well tissueculture plates containing 100 μL of an appropriate serum-free medium(Table 5). These cells were incubated in a 37° C. incubator under 5%carbon dioxide until the cells differentiated, as assessed by standardand routine morphological criteria, such as growth arrest and neuriteextension (approximately 3 days). The media from the differentiatedcells was aspirated from each well and replaced with fresh mediacontaining either 0 (untreated sample), 0.01 nM, 0.04 nM, 0.12 nM, 0.37nM, 1.1 nM, 3.3 nM, and 10 nM of a BoNT/A complex for cells comprising aSiMa or a PC12 transfected cell line; and 0 (untreated sample), 0.14 nM,0.40 nM, 1.2 nM, 3.7 nM, 11 nM, 33 nM, and 100 nM of a BoNT/A complexfor cells comprising a Neuro-2a transfected cell line. The cells weretreated with BoNT/A containing media for 6 hrs followed by incubationwith fresh media for 15 hrs and harvested by adding 40 μL of 2×SDS-PAGEloading buffer and heating the plate to 95° C. for 5 min.

To detect for the presence of SNAP-25 cleavage product, an aliquot fromeach harvested sample was analyzed by Western blot as described inExample I, except that harvested samples are separated by SDS-PAGE using12% 26-well Criterion gels (Bio-Rad Laboratories, Hercules, Calif.), andthe following primary antibodies were used a 1:1,000 dilution of rabbitpolyclonal α-SNAP-25 antibody serum (Example IV) (AGN, polyclonalantibody), a 1:500 dilution of α-FGFR2 rabbit polyclonal C-17 (SantaCruz Biotechnology, Santa Cruz, Calif.), or a 1:500 dilution of α-FGFR3rabbit polyclonal C-15 (Santa Cruz Biotechnology, Santa Cruz, Calif.).The intensity of the protein of interest from each sample was calculatedusing Image Quant (GE Healthcare, Piscataway, N.J.) and the EC₅₀ foreach of the cells lines was estimated using SigmaPlot software.

The results indicate that cells transfected with FGFR2 or FGFR3 weremore sensitive to BoNT/A than cells transfected with GFP and also showeda higher level of SNAP-25 cleavage (Table 14). The EC₅₀ values for cellsover-expressing FGFR2 or FGFR3 were lower than the EC₅₀ values exhibitedby cells over-expressing GFP, indicating that introduction of FGFR2 orFGFR3 improved cell susceptibility to BoNT/A intoxication or improvedBoNT/A uptake capacity.

TABLE 14 Effects of Introducing Exogenous BoNT/A Receptors on CellSusceptibilty to BoNT/A Intoxication or BoNT/A Uptake Cells TransfectedGene EC₅₀ (nM) Max Signal SiMa GFP 0.0812 ± 0.010 22,733,787 SiMa FGFR20.0459 ± 0.003 26,136,578 SiMa FGFR3 0.0377 ± 0.006 24,326,271 PC-12 GFP3.3362 ± 1.881 26,956,063 PC-12 FGFR2 0.3429 ± 0.059 25,376,114 PC-12FGFR3 0.2634 ± 0.026 24,102,459 Neuro-2a GFP  61.80 ± 9.710 4,605,974Neuro-2a FGFR2  31.59 ± 8.800 23,279,765 Neuro-2a FGFR3  11.55 ± 5.24028,347,413

Detection for the presence of SNAP-25 cleavage product can also beperformed using sandwich ELISA as described in Examples VI-X.

1. (canceled)
 2. (canceled)
 3. A method of quantifying picomolar amountsof botulinum neurotoxin serotype A (BoNT/A) activity in a sample, themethod comprising: a. obtaining a sample comprising BoNT/A or suspectedof comprising BoNT/A; b. contacting the sample with a plurality of cellsfrom an established cell line susceptible to intoxication by about 50 pMor less of a BoNT/A and expressing a SNAP-25 comprising a BoNT/Acleavage site; c. measuring a reporter signal that corresponds to theamount of a SNAP-25 cleavage product in the plurality of cells; and d.determining the BoNT/A activity in the sample by comparing the reportersignal measured in step (c) relative to a dose-response curve generatedby the method with a sample of known potency defined by mouse LD₅₀assay; wherein the method has an LOQ of <5 pM BoNT/A.
 4. The method ofclaim 3, wherein a fluorophore is utilized to generate the reportersignal in step (c).
 5. The method of claim 3, wherein a labeled antibodyis utilized to generate the reporter signal in step (c).
 6. The methodof claim 5, wherein the labeled antibody is an isolated α-SNAP-25antibody, comprising a heavy chain variable region comprisingcomplementary determining regions (CDRs) comprising the amino acidsequences of at least one of SEQ ID NOs: 93, 96, and 100 and a lightchain variable region comprising CDRs comprising the amino acidsequences of at least one of SEQ ID NOs: 105, 110 and
 115. 7. The methodof claim 3, wherein the method does not utilize fluorescence resonanceenergy transfer (FRET).
 8. The method of claim 3, wherein the SNAP-25 isa non-naturally occurring SNAP-25.
 9. The method of claim 8, wherein theestablished cell line has been engineered to express the non-naturallyoccurring SNAP-25.
 10. The method of claim 9, wherein the non-naturallyoccurring SNAP-25 comprises at least one fluorophore.
 11. The method ofclaim 9, wherein the non-naturally occurring SNAP-25 is greenfluorescent protein.
 12. The method of claim 3, wherein the sample isbulk BoNT/A drug substance.
 13. The method of claim 3, wherein thesample is a formulated BoNT/A pharmaceutical product.
 14. The method ofclaim 3, wherein the established cell line is a neuronal cell line. 15.The method of claim 3, wherein the established cell line is selectedfrom the group comprising: SiMa and Neuro-2a cell lines.
 16. The methodof claim 15, wherein the established cell line is a Neuro-2a cell line.17. The method of claim 3, wherein the method has an LOQ of <1 pMBoNT/A.
 18. The method of claim 3, wherein the cell is susceptible toBoNT/A intoxication by about 10 pM or less of a BoNT/A.
 19. The methodof claim 3, wherein the cell is susceptible to BoNT/A intoxication byabout 1 pM or less of a BoNT/A.
 20. The method of claim 3, wherein thesample comprises about 1 ng or less of a BoNT/A.
 21. The method of claim3, wherein the sample comprises about 10 pM or less of a BoNT/A.
 22. Anestablished cell line expressing SNAP-25 and susceptible to intoxicationby about 50 pM or less of a BoNT/A. 23-31. (canceled)